WESTERN CONNECTICUT STATE UNIVERSITY. Orographic Effect on Snow Crystal Structure ANNE MARIE PALUMBO, RYAN M. SUTER AND PAUL V.

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1 Spring 2010 ES/PHY 499 SENIOR RESEARCH WESTERN CONNECTICUT STATE UNIVERSITY Orographic Effect on Snow Crystal Structure ANNE MARIE PALUMBO, RYAN M. SUTER AND PAUL V. SHUPENIS

2 Spring 2010 ES/PHY 499 SENIOR RESEARCH 1 WESTERN CONNECTICUT STATE UNIVERSITY Orographic Effect on Snow Crystal Structure ANNE MARIE PALUMBO, RYAN M. SUTER AND PAUL V. SHUPENIS Physics, Astronomy, and Meteorology Department, Western Connecticut State University, Danbury, CT (Modified March 18, 2010) Abstract During coastal storms occurring on December 31, 2009 and January 3, 2010 snow crystal structures were observed and recorded at coastal, valley and control locations in southwestern Connecticut. Methodology was derived primarily from Bentley, Libbrecht, Magono, Lee, Peterson, Yeh, Cotton, Gold and Power. Snow crystal samples were classified according to Libbrecht s Basic Classification and the more complex meteorological classification of Magono and Lee. Results indicated differences in snow crystal structure, size, riming, and aggregation between locations. These characteristics may prove as indicators for locations as the distribution of aerosols during the winter season acts as a control for each location. Introduction Since the photographs of Bentley the research of snow crystals has become expansive including field and laboratory investigations. Upon examining the previous research of such predecessors, no research found has directly focused on observing snow crystal structures between three locations simultaneously as a means to identify location based upon snow crystal structure observed in a particular area. This research focuses on the three distinct locations of coastal, valley, and control as a means to characterize these areas. Aerosol distribution is distinct for each area and serves as the basis for reverse identification of snow crystal structure to location. Extensive results This research was conducted under the advisement of Dr. Albert Owino, Department Chair of Physics, Astronomy and Meteorology at Western Connecticut State University for Research courses ES/PHY 499 and MTR 450. will be discussed for each location and compared in order to obtain a specific description for each site. Hypothesis: If snow crystals are collected at various orographic locations then the location will be a determining factor in the production of the snowflake s crystalline structure characteristics. Further Questions: (1) Does location have an effect on the crystalline structure of snowflakes? (2) How influential is the progression of the storm s passage? (3) Does a particular snow crystal structure predominate at a given orographic location? (4) Can a location be identified based upon snow crystal structures observed? Previous research: This research focuses on the experiments that have primarily taken place in the field as our research replicates. Their methodologies range from observations to preservation of snow crystals.

3 Spring 2010 ES/PHY 499 SENIOR RESEARCH 2 Bentley: Bentley developed the technique to collect and photograph snow crystals. As he described in the article Photographing Snowflakes, (1922) the process begins by using a 1 ft. x 1 ft. chilled black chalk board with wire handles to collect the snow crystals. A feather duster serves the purpose of clearing the board every few minutes until a desired specimen is captured. Observation of the snow crystals is done via the naked eye or by utilizing a magnifying glass. Bentley then describes using a sharp-ended wooden splint to transfer the snow crystal to a microscope slide inside his barn. He cautions against breathing on the snowflake and to work quickly. The snowflake is then photographed utilizing a compound microscope attached to a camera of sorts. The production of the photograph is described in detail as well, but as no photographs will be taken in our research it will not be discussed here. In the article Snow Beauties (1910) Bentley states, I have secured sixteen hundred photo-micrographs of snow crystals alone, and no two are alike. Even though direct recording of weather data was not done for each snowflake photographed, Bentley observed that the structure of the snow crystals depended greatly on the atmospheric processes at work during a snow storm. In the same article he also stated, As a rule, low clouds, if relatively warm, tend to produce the more rapidly growing open branching forms, and the intermediate and upper, if relatively much colder, the more solid, close columnar and tabular forms. In the later 1922 article Photographing Snowflakes, Bentley further describes, the western quadrants of widespread storms or blizzards furnish the most beautiful and perfect forms the wind is usually westerly or northerly, with the barometer standing at 29.6 to 29.9 in. and slowly rising The character of the snowfall often undergoes quite abrupt changes as the storm progresses. It is for this finding of Bentley s work that we have decided to record weather data to take into consideration the variable of the snow crystal s change in structure due to the shift in the storm in addition to variance in location. Magono & Lee: Magono and Lee believed that the Nakaya s classification was insufficient in the classification of nonsymmetric and irregular snow crystal formations. For their research, Magono and Lee gathered over thirty-thousand samples and preformed several laboratory experiments to begin classifying the irregulars. From Magono and Lee s observations a new classification chart including irregular snow crystal formations was constructed. (Magono & Lee, 1966) The new classification chart provides a detailed view of all the possible snow crystal formations, including any snow crystals that undergo any transformations (such as riming and aggregation) while descending. (Fig. 4b) Libbrecht: In his Field Guide to Snowflakes Libbrecht outlines observation and collection methods of snow crystals by combining the older ways of Bentley, Magono & Lee, and others as well as modern methods he has devised. (Libbrecht, 2006) Libbrecht has collected numerous samples and made precise measurements to examine the effects of temperature on the growth rate of snowcrystals in the field as well as laboratory work at Caltech. His intensive research has explored the basics of snow crystal structure to the physics behind them. In the field Libbrecht catches snow crystals on a dark colored collection board. After selecting the snowflake he wishes to photograph he uses a small artist s paintbrush to transfer the snowflake to a glass microscope slide. The slide is then placed under the microscope where Libbrecht quickly photographs the specimen prior to sublimation or melting. (p. 105) Libbrecht then chooses to categorize the snow crystals largely according to their growth behavior to avoid further ambiguity present in all attempts at classification. (p. 31) This basic classification system will be utilized in our research.

4 Spring 2010 ES/PHY 499 SENIOR RESEARCH 3 Peterson, Yeh & Cotton: The field guide compiled by Peterson, Yeh and Cotton contains detailed classifications and instructions of techniques for capturing, preserving and photographing snow crystals. A detailed chart for the collection and classifying of snow crystal structures in the field is provided. The processes of riming and aggregation were accounted for in the field chart. We will also account for riming and aggregation in our observations as well. Gold & Power: In the article Correlation of Snow Crystal Type with Estimated Temperature of Formation Gold and Power briefly outline their findings after collecting raw data of snow crystal structures during thirty-three different snowstorms. Collection consisted of recording snow crystal type in the field by observation. Cloud temperatures were then deduced from synoptic data and radiosonde reports. Field observations were in accordance with the laboratory findings of Nakaya (Gold & Power, 1952). Certain snow crystal structures were discovered to develop at defined cloud temperature ranges. These results prove that field tests are successful and give an accurate gauge to estimate cloud temperature. Method The methodology is primarily derived from the work of Bentley, Libbrecht, Magono and Lee. Initial planning was to collect snow crystals on glass slides through an acrylic replica method and photograph each slide; however this proved to be unsuccessful as the sampling error would be far larger due to collection limitations. Therefore recording of snow crystal structure and size was conducted in the field prior to melting. Rather than using a blackboard like Bentley, laminated collectors were created to substitute for the blackboard. The first classification is derived from Libbrecht s basic classification of snow crystals, as outlined in his Field Guide to Snowflakes. Magono and Lee s classification system, which is considered the official classification system by meteorologists, will constitute the second classification of greater detail. Field collection charts were a variation of those offered by Peterson, Yeh and Cotton and accounted for riming. Weather data was also be recorded in accordance to Bentley s observations. Further analysis will reference the work of Gold and Power in comparing cloud temperature for each location. a. Collection Locations Data was collected among three joint experiments at three separate locations. The orographic effect at each of these locations is expected to be unique to the particular region thus resulting in different snow crystal structure types observed. All locations are located within southwestern Connecticut. (Fig. 2) Control: Southbury, CT will constitute as the control location as it is located inland with flat surroundings and relatively unaffected by orographic effects. The collection site is at an elevation of 256 ft. and conducted by Ryan M. Suter. Coastal: Weston, CT will constitute as the coastal location as it is located near Long Island Sound. The collection site is at an elevation of 50 ft. and conducted by Anne Marie Palumbo. Valley: Naugatuck, CT will constitute as the valley location as it is located in the Naugatuck Valley to the northeast of the city. The collection site is at an elevation of 520 ft. and conducted by Paul V. Shupenis.

5 Spring 2010 ES/PHY 499 SENIOR RESEARCH 4 Topographic Maps of Collection Locations Figure 2 - Data Sites: USGS Maps of all collection locations in relationship to one another both with the coast (fig. 2a) and with increased resolution to one another (fig. 2b). Locations are as follows: coastal (blue), control (red) and valley (yellow).

6 Spring 2010 ES/PHY 499 SENIOR RESEARCH 5 b. Weather Data Weather data recorded during data collection were obtained via local weather stations. Variables recorded include: storm condition, surface temperature, wind chill, humidity, dew point, wind, and barometric pressure. Visibility, cloud elevations, and conditions were recorded when available. Fig. 1 is an excerpt of weather data recorded during collection. Collection Date: 12/31/09 Time Period of Collection: 9:15 AM 10:30 AM Storm Condition: Light snow c. Collection Procedure The following collection procedure was devised to maintain consistency at all collection sites. All documents referred to may be found in the Appendixes. Collection materials include the Field Collection Chart, laminated classification charts, Snow Crystal Collector, ruler, and loupe. The loupe utilized was a Belomo 10x Triplet Loupe Magnifier which we found suitable for identifying snow crystal structures, however a greater magnification would be desired to identify minute structures including germs. The procedure executed is as follows: 1. Contact group about upcoming storm. Temperature: F Humidity: 86% Wind: Calm Visibility: 2.5 miles Wind chill: 28 0 F Dew Point: 25 0 F Pressure: in (Rising) Clouds: Mostly cloudy 2400 ft, 4100 ft; Overcast 4800 ft (Above ground level) Figure 1 - Example of Weather Data: A partial example of weather data recorded for each 25 snow crystal samples. This particular excerpt was for the coastal location. Weather data was recorded for every twenty-five snow crystals samples observed in order to take the progression of the storm and atmospheric environment into account. Averages were then calculated for each storm, as well as for the entire collection duration of this research. Profiles were also compiled for the storms during which data collection occurred. Information recorded includes the type of storm, date of passage, time period of collection within the storm, and a brief meteorological description. 2. Place laminated Field Collection Chart, Snow Crystal Collector, and Magono & Lee Snowflake Classification System outside to chill along with a writing utensil and loupe. (You may wish to keep these in your freezer.) 3. Begin to fill out Official Collection document electronically concerning the current weather conditions right before beginning collection. 4. Go outside to collect snowflakes on collector. 5. Examine each snow crystal quickly prior to melting. (This is easiest under some type of overhang outside, like a porch. Try not to breathe on the snow crystal.) 6. Record basic classification number, Magono & Lee classification number, whether or not there is riming, the size, and any other observations as time permits. (Fig. 3)

7 Spring 2010 ES/PHY 499 SENIOR RESEARCH 6 7. Collect at least 50 crystals per snow event, up to 200 samples if possible. For every 25 samples record weather data. 8. Wipe Field collection chart clean to prepare for next collection. 9. Go inside and transfer data to official electronic copy listing both the number and full classification name. 10. Complete analysis section of Official Collection document including the averaging of weather data and completion of snow crystal structure charts. (Edit data tables as needed.) Chart but is typed for distribution purposes between location sites. d. Classification The first classification is derived from Libbrecht s basic classification of snow crystals, as outlined in his Field Guide to Snowflakes. (2006, p. 31) Magono and Lee s classification system, which is considered the official classification system by meteorologists, will constitute the second detailed classification. (Meteorological Classification of Natural Snow Crystals, 1966, p ) Forward results to group. 12. Complete Official Averages of Region once all desired samples are collected Begin Analysis Sample # Basic Classification Magono & Lee Classification Riming Size (mm) Other Observations P1d P6d 1.2 M & L better P3b 1.0 Basic better 4 20 P1c 2.0 Perfect Structure a X 4 Slight riming a 1.5 Perfect branches C2a R2b X R3b X 1.7 Moderate riming ~10 Am Cluster w/ radiating N1a 2.0 Figure 3 - Example Collection Chart: A partial example of the Collection Chart utilized to record data. The same chart constitutes the Field Collection

8 Spring 2010 ES/PHY 499 SENIOR RESEARCH 7 Time Period of Collection: 9:15 AM 12:30 PM EST Description: Figure 4 - Classification Charts: Classifications used in recording of snow crystal structure observations including Libbrecht s Basic Classification (fig. 4a) and the more detailed classification by Magono and Lee (fig. 4b). The basic classification chart (Fig. 4a) is a breakdown of all the common snow crystal formations. This chart is more for identifying the basic snow crystal formations and does not provide much insight into the affects of the atmosphere on the formation of snow crystals. The Magono and Lee classification chart (Fig. 4b) is more detailed than the basic classification chart by expanding on the irregular snow crystals to include the effects of riming and aggregation. All snow crystals rimed, aggregated or deformed have a separate break down which offers greater insight into the affects of the atmosphere on snow crystal formation. Note that the number of samples indicating a particular structure type will be less with Magono and Lee as basic structures are classified in more detail. For example, structures that are rimed are classified under a different structure even though the underlying of the structure may be dendritic or stellar. It appeared to be a coastal storm that formed off the coast of the Carolinas which combined with another storm that moved in from the Midwest. Not a very strong system but it did result in the dropping of 2-4 inches of snow in most areas. Some other areas around the state saw higher amounts from this system. Weather Maps: Storm 1 Results 1. Storm 1 Type: Coastal Date: 12/31/09

9 Spring 2010 ES/PHY 499 SENIOR RESEARCH 8 Snowfall from this storm ranged from 3-5 inches across the state, with some areas seeing higher amounts in the way of snow drifts due to the gusty winds. Figure 5 - Storm 1 Weather Maps: Surface weather maps of costal storm that occurred on December 31, 2009 from HPC (fig. 5a) and NOAA (fig. 5b). 2. Storm 2 Weather Maps: Storm 2 Type: Coastal Date: 1/3/10 Time Period of Collection: 3:00 PM 5:00 PM EST Description: The snowfall from this storm was caused by the remnants of a small low pressure system that was located off the coast of Maine. The moisture the Atlantic Ocean fed into the system drove the storm back into the region. Dynamics were favorable for snowfall. The temperatures at the surface were cold enough to support a snow event.

10 Spring 2010 ES/PHY 499 SENIOR RESEARCH 9 a. Crystal Structures Figure 6 - Storm 2 Weather Maps: Surface weather maps of costal storm that occurred on January 3, 2010 from HPC (right: fig. 6a) and NOAA (above: fig. 6b). 3. Control Location Figure 7 - Control Location: USGS map of control location site in Southbury, CT. Overall 100 snow crystal samples were collected and identified over the course of two storm systems for the control location. Using the basic classification the predominate snow crystal structures for the control region are hexagonal plates (#2) and stellar dendrites (#6). Of the 100 samples, twenty were identified as hexagonal plates (#2) and eighteen were identified as stellar dendrites (#6). Using the Magono & Lee classification chart the predominate snow crystal structures are crystals with broad branches (P1c), ordinary dendritic crystals (P1e), and hexagonal plates (P1a). Of the 100 samples sixteen were identified as crystal with broad branches (P1c), sixteen were identified as ordinary dendritic crystals (P1e), and fifteen were identified as hexagonal plates (P1a). For Storm 1, which occurred on December 31, 2009, fifty snow crystals were observed and identified. Based on the basic classification chart the predominate snow crystal structures are hexagonal plates (#2) and simple needles (#12). Of the fifty samples fourteen were identified as hexagonal plates (#2) and nine simple needles (#12). Based on the Magono & Lee classification chart the predominate snow crystal structures are hexagonal plates (P1a) and elementary needles (N1a). Of the fifty samples fourteen were identified as hexagonal plates (P1a) and six were identified as elementary needles (N1a). For Storm 2, which occurred on January 3, 2010, fifty snow crystals were collected and identified. Based on the basic classification chart the predominate snow crystal structures are simple stars (#5) and fernlike stellar dendrites (#7). Of the fifty samples twelve were identified as simple stars (#5) and twelve were identified as fernlike stellar dendrites (#7). Based on the Magono & Lee classification chart the predominate snow crystal structures are crystals with broad branches (P1c) and ordinary dendritic crystals (P1e). Of the fifty samples thirteen were identified as crystal with broad

11 Spring 2010 ES/PHY 499 SENIOR RESEARCH 10 branches (P1c) and twelve of them were identified as ordinary dendritic crystals (P1e). b. Crystal Size Overall the size distributions of the 100 snow crystal structures range from a minimum of 0.55 mm to a maximum of 6.80 mm with an average size of 3.04 mm The storm that occurred on December 31, 2009 had a minimum snow crystal size of 0.66 mm and a maximum snow crystal size of 6.80 mm. The fifty snow crystals that were collected had an average size of 3.73 mm. Of the fifty samples collected, observations indicated that the snow crystals of greater size were stellar dendrites (#6). The storm that occurred on January 3, 2010 had a minimum snow crystal size of 0.55 mm and a maximum snow crystal size of 6.40 mm. The fifty snow crystals that were collected had an average size of 2.36 mm. Of the fifty samples collected, observations indicated that the snow crystals of greater size were fernlike stellar dendrites (#7). When observing both storm systems it is evident that the snow crystal size varied from minimum to maximum size as the storm migrated over the Southbury. c. Atmospheric Processes The Morphology Diagram found in Libbrecht s Field Guide to Snowflakes (2006, p. 11) depicts the change in snow crystal structure with the amount of supersaturation and temperature of the atmosphere (Fig. 8). Based on the types of snow crystals collected in the control region the cloud temperatures ranged from 20 F (-5 C) to -30 F (-35 C). Figure 8 - Morphology Diagram: The Morphology diagram illustrates the effect of supersaturation and temperature on the formation of snow crystal structure. (Libbrecht, 2006, p. 11) Supersaturation is the amount of water vapor contained in a fluid - in this case the atmosphere. Fig. 8 depicts the change in snow crystal structure with the amount of supersaturation in the atmosphere. The control region contained a combination of plates, dendrites, and columns. Weather data collected for the region indicates the region s average temperature was 21.1 F and dew point was 13.5 F. For Storm 1 the average temperature was 26.9 F and the average dew point was 16.5 F. For Storm 2 the average temperature was 15.3 F and the average dew point was -4 F. Based on the Morphology Diagram the control region had a supersaturation range from 0.1 g/m 3 to 0.3 g/m 3. Collision and Coalescences is defined as the growth process of a larger cloud droplet colliding with smaller cloud droplets which forms a larger droplet to the point where the droplet becomes large enough to overcome the force of gravity and begin to fall out of the cloud environment. Water vapor is the gaseous form of water and the amount of water vapor in the atmosphere is known as relative humidity. The more humid the air the moister the snow fall will be, and the less humid the air the dryer the snow fall will be. The average humidity for the controlled region was 51.5%. Based on this

12 Spring 2010 ES/PHY 499 SENIOR RESEARCH 11 percentage one can deduce that the storms in this region had moderately moist, loose snow. Storm 1 had a humidity of 63%. Based on this percentage the snow fall of this storm was moist and compacted easily. The increase in moisture made the snow fall very dense and heavy. Storm 2 had a relative humidity of 40%. Based on this percentage the snow fall of this storm was dryer and looser as compared to Storm 1. The decrease in moisture content made the snow less dense and loose. d. Riming & Aggregation At the control location 4% of the snow crystals collected indicated riming. Riming is the process of super-cooled water making contact with ice or snow particles. (Peterson, Yeh & Cotton, p. 13) From the one hundred snow crystals collected and identified in the control region none were identified to have undergone growth by aggregation. Aggregation is the process of snow crystals making contact with other snow crystals to form larger snow crystals. (Peterson, Yeh & Cotton, p. 15) 4. Coastal Location Figure 9 - Coastal Location: USGS map of coastal location site in Weston, CT. a. Crystal Structures A total of one hundred and fifty snow crystal structures were observed and recorded over the course of two coastal storms occurring on December 31, 2009 and January 3, 2010 with seventy-five samples recorded for each storm. During Storm 1 the predominate structures according to the Basic Classification were a total of 22 stellar dendrites (#6), 18 graupel (#18), 7 simple stars (#5), 5 fernlike stellar dendrites (#7), 5 radiating dendrites (#32), 4 double plates (#20), 3 needle clusters (#13), and 3 irregulars (#33). According to Magono and Lee classification the predominate snow crystal structures were a total of 9 lump graupel (R4b), 7 stellar crystals (P1d), 5 densely rimed stellar crystal (R2b), 5 conelike graupel (R4c), 4 crystal with broad branches (P1c), 4 fernlike crystals (P1f), 4 malformed crystals (P5), 4 graupel-like snow of lump type (R3b), 4 hexagonal graupel (R4a), 3 ordinary dendritic crystals (P1e), and 3 rimed stellar crystals (R1d). Dendritic structure types and graupel dominated during this storm. It is important to note that the structures were observed to be partially dependent on the period of time collection within the storm. As Storm 1 progressed there was a change to riming and graupel predominating.

13 Spring 2010 ES/PHY 499 SENIOR RESEARCH 12 During Storm 2 the predominate structures according to the Basic Classification were a total of 22 radiating dendrites (#32), 19 stellar dendrites (#6), 11 irregulars (#33), 10 simple stars (#5), 4 stellar plates (#3), and 4 graupel (#35). According to Magono and Lee classification the predominate snow crystal structures were a total of 13 radiating assemblage of dendrites (P7b), 11 ordinary dendritic crystals (P1e), 9 stellar crystals (P1d), 9 graupel-like snow of lump type (R3b), 8 rimed broken branches (13b), 6 dendritic crystal with sector-like ends (P2d), and 3 broken branches (13a). Dendritic structure types, irregulars such as broken branches, and graupel dominated Storm 2. The most common structure type according to Magono and Lee s classification was the radiating assemblage of dendrites (P7b), which was only seen once in the duration of collection for Storm 1. Structure is clearly partially dependent on the characteristics of the storm itself and period of collection as the storm progresses. Figure 10 - Graupel: A photograph of graupel taken at the coastal location after a storm. The graupel is primarily Conelike and lies on top of radiating dendrites and stellar crystals. (Palumbo) To summarize the predominate structures for the coastal location during both Storm 1 and Storm 2 snow crystal structures occurring more than ten times will be mentioned here. According to basic classification there were observed a total of 41 stellar dendrites (#6), 27 radiating dendrites (#32), 22 graupel (#35), 17 simple stars (#5), and 14 irregulars (#33). According to Magono and Lee s classification there were 16 stellar crystals (P1d), 14 ordinary dendritic crystals (P1e), 14 radiating assemblage of dendrites (P7b) and 10 lump graupel (R4b). The coastal area can thus be classified as have snow crystal structures predominating as stellar crystals, dendritic type crystals, radiating assemblages of dendrites, graupel (Fig. 10), and irregulars. b. Crystal Size Snow crystal size for the coastal location ranged from 0.5 mm to 7.0 mm with the average size for both Storm 1 and Storm 2 being 2.35 mm. During Storm 1 the range was slightly smaller from 0.5 mm to 5.0 mm with an average size of 2.3 mm. During Storm 2 the snow crystals sampled were slightly larger than in Storm 1 with an average size of 2.8 mm. The minimum size was 1.0mm, while the maximum size was 7.0 mm. It is important to note that the size changed with the progression of the storm. This is evident by analyzing each storm in twentyfive sample intervals. For the storm on December 31 the snow crystal size can be noted to increase then decrease over a 3.25 hour period (9:15 AM to 12:30 PM EST). For samples 1 to 25 the average crystal size was 2.3 mm with a range from 1.0 mm to 5.0 mm. For samples 26 to 50 the average size is greater at 2.8 mm with the same range as samples 1 to 25. For samples 51 through 75 the average size decreases to 1.8 mm with a minimum size of 0.5 mm to 4.0 mm. For the storm on January 3 the snow crystal size can be noted to increase then decrease as well over a 3.42 hour period (12:45 PM to 4:10 PM EST). For samples 1 to 25 the average crystal size was 2.4 mm with a range from 1.0 mm to 5.0 mm. For samples 26 through 50 the average crystal size increased to 3.3 mm with a greater range from 1.0 mm to 6.0 mm. Samples 51 to 75 then decreased in

14 Spring 2010 ES/PHY 499 SENIOR RESEARCH 13 average size to 2.7 mm. The minimum size was 1.0 mm and the maximum size was 7.0 mm, the largest of all samples collected. c. Riming & Aggregation Out of the 150 samples observed and recorded at the coastal location 70 samples indicated riming (46.67%). A greater amount of riming occurred during Storm 1 than Storm 2 at 50.67% (38 rimed samples of 75) compared to 42.67% (32 rimed samples of 75). As compared to the control and valley locations this amount of riming is quite extensive and characteristic to the coastal location, which will be discussed later. The amount of riming varied throughout both storms as well, which is evident analyzing each twenty-five sample set. For the storm occurring on December 31 riming decreased then increased. Samples 1 through 25 had 12 rimed samples, compared to 7 rimed crystals for samples 26 to 50 and 19 rimed crystals for samples 51 to 75. For the storm occurring on January 3 riming increased then decreased. For samples 1 to 25 only 3 of the crystals were rimed. Samples 26 to 50 had a dramatically higher rate of riming at 21 rimed crystals. This was followed by a decrease to 8 rimed crystals for samples 51 to 75. Graupel is a result of extensive riming. Examining the size of graupel with the change in surface temperature shows the influence of storm characteristics on the amount of riming present. (Fig. 11) The largest range of graupel diameters correspond to warmer surface temperatures. As with snow crystal structure and size, riming is dependent on the storm and the period of collection during the storm s progression. Despite these variables, the coastal location proves to be of upmost importance as indicated by the unique frequency of riming. This can be explained by the fact that near the coast there is a greater abundance of moisture. This will be discussed in further detail while analyzing atmospheric processes. Figure 11 - Graupel Size vs. Surface Temperature: This graph depicts the size of graupel samples collected at the coastal location compared to surface temperature. To note multiple data points overlap at 31.4 o F. Overlapping is partially due to surface temperature being recorded for every 25 samples rather than each sample individually. Aggregation was especially evident during Storm 2 for samples 51 through 75. Within the ten minutes it took to recollect the weather data for the sample set the snow crystal structure changed from moderate riming of stellar dendrites and braches to extensive aggregates. As referenced under the control location, aggregation is the grouping together of snow crystals that occurs depending on the snow crystal structures and the temperature. Most of the aggregates observed were simple aggregates made of two to three crystals. However some mature aggregates (four or more snow crystals) were observed as well, but fell apart upon impact of the collection board. (Peterson, Yeh & Cotton, Field Guide, p. 14) All aggregates observed were comprised of radiating dendrites (#32 for basic classification, P7b for Magono and Lee classification). The radiating dendrites appear to be well suited for aggregation due to the interlocking nature of the branches. To note, the cloud elevation was 1500 ft. during this point of the storm, lower than the previous sample collection (samples 26 to 50) at 2400 ft., indicating a warmer cloud region. This data is in accordance with Bentley who stated, As a rule, low clouds, if relatively

15 Spring 2010 ES/PHY 499 SENIOR RESEARCH 14 warm, tend to produce the more rapidly growing open branching forms, and the intermediate and upper [clouds], if relatively much colder, the more solid, close columnar and tabular forms. (Snow Beauties, 1910) Also note, aggregation can also occur among other crystal types as well but none were observed here. Wallace and Hobbs mention that aggregation is more likely to occur when riming is present due to the difference in terminal velocities that results from riming. Also dendrites have a greater adhesive property as they interlock. At warmer temperatures above -5 o C the surface of ice develops a sticky property leading to further aggregation. (2006, p. 243) Figure 12 - Clouds with Ice Particles: Ice particles existing within marine (red) and continental (blue) clouds vs. temperature. (Wallace and Hobbs, 2006, p. 236) d. Atmospheric Processes Examining the atmospheric processes present at the coastal location the physical characteristics of the snow crystal structures observed can be explained. Prior to analyzing the atmospheric processes occurring, the environment of the atmosphere must first be described. The snow collected was formed in a mixed cloud where ice particles and super-cooled water droplets coexist as evident by riming occurring. (Wallace and Hobbs, 2006, p. 237) Riming occurs when super-cooled water droplets freeze upon contact with the ice nuclei. As ample rimed snow crystals were produced one can deduce that the coastal environment is rich in supercooled water droplets as well as ice particles. Wallace and Hobbs confirms this observation. In Fig. 12 the marine environment is shown to have a higher percentage of clouds containing ice at warmer temperatures versus continental. As seen in Fig. 13 ice particle concentrations are in greatest concentrations in a marine environment at warmer temperatures. This is crucial to note as greater quantities of supercooled water droplets explain the unusually high riming rate at the coast. Figure 13 - Ice Particle Concentration: Ice particle concentrations are illustrated vs. temperature of cloud top. Marine clouds are designated by blue and continental clouds are designated by red. (Wallace and Hobbs, 2006, p. 236) The role of sea salt particulates serving as cloud condensation nuclei (CCN) may attribute to the increased amount of ice particles in the marine environment as compared to continental. The marine environment is unique to the coastal location compared to industrial sources of the valley and control sites. The significance of aerosols will be examined in greater depth in the discussion. The coastal environment also proves to be warmer than the valley and control environments with an average temperature of 24.7 o F for the total collection of both storms (valley average was 20.8 o F and control average was 21.1 o F). This leads to a greater tendency of

16 Spring 2010 ES/PHY 499 SENIOR RESEARCH 15 aggregation and the development of larger snow crystals through aggregation. (To note, the largest snow crystals were not always seen at the coast. This discrepancy between our findings and theories will be discussed.) The coastal snow is characterized by high moisture and compaction. The average humidity at the coastal location (87%) was greater when compared to the valley (82.5%) and control (51.5%) sites. This influences heavily on the snow crystal structure type observed as evidenced by Magono and Lee (refer to Fig. 14). 5. Valley Location Figure 15 - Valley Location: USGS map of valley location site in Naugatuck, CT. a. Crystal Structures Figure 14 - Temperature and Humidity Conditions: With increasing humidity and temperature snow crystal structure is altered. (Magono & Lee, 1966, p. 327) The more complicated crystal structures are seen to develop with an increase in vapor supply (humidity) and an increase in temperature. The structures observed at the coast can be identified to have a temperature of 0 to -20 o C within the cloud environment, primarily above the water saturation line. This also corresponds directly to the morphology diagram within this same temperature range for high supersaturations (see Fig. 8). 100 samples were observed for the valley location with 50 for each storm. The two predominant types of snowflake crystalline structures that were seen for Storm 1 were stellar dendrites (#6) and simple needles (#12). Under the Magono and Lee system the predominant crystalline structures were plates with dendritic extensions (P2g) and elementary needles (N1a). For Storm 2 the most prominent structures under the basic classification were simple needles (#12) and needle clusters (#13). Under Magono and Lee the most prominent structures consisted of elementary needles (N1a) and bundles of elementary needles (N1b). b. Crystal Size The sizes of the snow crystals that were observed varied for each storm. For Storm 1 there was a minimum crystal size of 1 mm and a maximum crystal size of 7mm. The average snow crystal size was 2.76 mm. For Storm 2 there was a minimum crystal size of 1 mm and a maximum crystal size

17 Spring 2010 ES/PHY 499 SENIOR RESEARCH 16 of 5 mm. The average snow crystal size was 1.9 mm. The size of a snow crystal is dependent on several key factors. The first factor is the amount of moisture present in the atmosphere and whether or not supersaturation exists. A second key factor is the temperature of the clouds the precipitation is maturing within. These temperatures will also determine the type of snow crystals that form. not freeze at 0 C but at much lower temperatures as they can become super cooled in the atmosphere. c. Atmospheric Processes The shape of the snowflake is determined by the temperature and humidity at which it is formed. Planar crystals grow in air between 0 C and 3 C. Between 3 C and 8 C, the crystals will form needles or hollow columns or prisms. From 8 C to 22 C, the shapes tend to form as plate-like, often with branched or dendritic structures to them. At temperatures below 22 C, the crystal development becomes more column-like in their development. (Walk, 2010) When comparing this to the data that was collected for this location the most common temperature range during the time of collection was between 3 C and 8 C. This can be determined because there was predominantly needles present during the collection time of the storms. If the temperatures were warmer, the location would have seen more planar shaped snow crystals and if the cloud environment was colder, then the samples would have been more column rather than being more needle like in nature. These temperatures are very important and even a slight change could greatly affect the type of snow that will fall to the ground. With steady riming graupel can form. Ice pellets and snow pellets are types of graupel that can fall that are associated with wintry precipitation. The Bergeron process relies primarily on the fact that the saturation vapor pressure with respect to ice is less than the saturation vapor pressure with respect to water. Another important factor is that pure water droplets do Figure 16 Water Amount vs. Temperature: The amount of the water in the air at 100% relative humidity and 50% relative humidity. (Wikipedia) Temperature RH wrt * H 2 O(liq) RH wrt H 2 O(ice) 0 C 100% 100% -05 C 100% 105% -10 C 100% 110% -15 C 100% 115% -20 C 100% 121% *wrt = with respect to Table 1 SVP: This table of temperature and relative humidity portrays the differences in saturation vapor pressures of water. (Nexlab) Fig. 16 shows if the temperatures at the surface increases, then the amount of water vapor at a given location will also increase. This can greatly change the type of snow crystal that will form and fall to the surface. Table 1 displays the relative humidity (RH) of water and ice compared to the temperature of the atmosphere. If the temperatures are cold enough, then supersaturation with respect to ice occurs. With

18 Spring 2010 ES/PHY 499 SENIOR RESEARCH 17 respect to water, the RH stays at 100% in most cases. Through the Bergeron process, it is seen that the RH values then grow to over 100% which would then put the atmosphere in super saturation conditions. In short summary, the ice crystal grows through sublimation at the expense of the super cooled water droplet. inversion, then the riming and aggregation results would have changed. The reasoning behind this thought is that if warmer temperatures are trapped at the surface due to an inversion, then the amount of water vapor present would increase. If an increase in water vapor exists in the atmosphere, then a greater amount of riming would result. d. Riming & Aggregation No samples were identified as aggregates. Riming was observed with 26% of the snow crystals, but was minimal in all cases. In addition, it can be implied that if there was some sort of a temperature Figure 17 - Basic Structure Classification: Percentages of snow crystal structure type based on Libbrecht s Basic Classification for control (fig. 17a), valley (fig. 17b) and coastal (fig. 17c).

19 Spring 2010 ES/PHY 499 SENIOR RESEARCH 18 Figure 18 - Magono and Lee Structure Classification: Percentages of snow crystal structure type based on classification by Magono and Lee for control (fig. 18a), valley (fig. 18b) and coastal (fig. 18c)

20 Spring 2010 ES/PHY 499 SENIOR RESEARCH 19 Discussion a. Comparisons between Locations i. Control vs. Valley The structure comparison between the control location and the valley location are very similar. By examining the pie charts of the structure distribution for the basic classification (refer to Figure 17a and 17b) one can see that the same crystal types were evident in both regions, but in varying amounts. The valley region received eight different types of snow crystal structures and these types are broken down in Figure 17b. The control region received ten different types of snow crystal structures and these types are illustrated in Figure 17a. Based on these results both regions collected stellar dendrites of approximately the same amount with the valley collecting 20% and the control collecting 19%. Other than the stellar dendrites, both locations collected different snow crystal structures. The main crystal structures collected at the valley region were simple needles at 31% and radiating dendrites at 15%. The main crystal structures collected at the control region were hexagonal plates at 21% and sectored plates at 13%. The primary difference between the valley region and the control region is that the valley collected 94% complex dendrites and needles, while the control region collected plates and simple dendrites at 77% of samples in these categories. By examining the pie charts of the structure distribution for the Magono & Lee classification (refer to Figure 18a & 18b) one can see that the same crystal types were prevalent in both regions. The valley region received five different types of snow crystal structures and these types are broken down in Figure 18b. The control region received four different types of snow crystal structures and these types are shown in Figure 18a. Based on these results both regions collected plane and needle crystals: 91% in the valley region and 96% in the control region. The difference in the regions is the amount of each crystal type collected. The valley region collected 55% plane crystals and 36% needle crystals. The control region collected 80% plane crystals and 16% needle crystals. On average the snow crystals collected in the valley region are 23% larger than the snow crystals collected in the control region. The average size of the snow crystals collected in the valley region was around the size of 3.71 mm. The average size of the snow crystals collected in the control region was around 3.04 mm. Both regions received a good mixture of large, medium and small snow crystal sizes. The structure that was consistent for both locations was the stellar dendrites. From the data collected the stellar dendrites were consistently the largest snow crystals collected. ii. Control vs. Coastal The structure comparison between the control location and the coastal location reveal strong differences. Examining the pie charts of the structure distribution for the basic classification (refer to Figure 17a & 17c) one can see that many of the same crystal types were prevalent in both regions. The coastal region received fifteen different types of snow crystal structures as characterized in Figure 17c. The control region received ten different types of snow crystal structures and these types are broken down in Figure 17a. The first disparity between the snow crystals collected in the coastal region versus the control region is the difference in the amount of snow crystal types. The coastal region collected over fifteen different types of snow crystals and the control region collected only ten types of snow crystals. The snow crystal structures collected at the coastal region range from needles to plates to dendrites to irregulars, while the snow crystal structures

21 Spring 2010 ES/PHY 499 SENIOR RESEARCH 20 collected at the control region are mostly simple dendrites and plates. The main crystal structures collected at the coastal region were stellar dendrites at 27% and radiating dendrites at 18%. The main crystal structures collected at the control region were hexagonal plates at 21% and sectored plates at 13%. Examining the pie charts of the structure distribution for the Magono & Lee classification (refer to Figure 18a & 18c) it is evident that the coastal region received a wider range of snow crystal structures than the control region. The coastal region received five different types of snow crystal structures and these types are displayed in Figure 18c. The control region received four different types of snow crystal structures and these types are broken down in Figure 18a. Based on these results the amount and type of snow crystal structures between the two regions was very different. The control region received twice as many plane crystals and needle crystals at 80% and 16% than the coastal region which received only 43% and 7% respectively. The coastal region collected greater amount of rimed crystals than the control region as well. The coastal region received 46.7% rimed crystal structures while no riming was observed at the control region. The coastal region collected more irregular samples at 13% than the control region which collected only 1% irregulars. The column crystal structure was the only type that was nearly the same at both control and coastal at 3% and 2% respectively. On average the snow crystals collected at the coastal region are 21% smaller than the snow crystals collected in the control region. The average size of the snow crystals collected in the coastal region was around the size of 2.35 mm. The average size of the snow crystals collected in the control region was around 3.04 mm. Based on predictions before the data was collected it was expected that the coastal region would have on average the largest snow crystals of the three locations. As the data indicates, the coastal region displayed the smallest on average crystal sizes for the entire array of data (Fig 21c) and Storm 1 (Fig. 21a). For averages during Storm 2 the coastal region was the greatest on average at 3.0 mm compared to the control region at 2.36 mm (Fig. 21b). To note, the coastal region did contain the largest individual snow crystals than any other regions with eleven of the samples collected measuring 5 mm or greater with a maximum size of 7 mm. If a larger sampling over various storms was collected the data would likely reflect larger snow crystals averages for the coastal location. The data collected by Gold & Power shows that temperature affects the type of snow crystal structure. Their results (Fig. 19) are consistent with the results of the samples collected at the coastal and control sites. At the coastal region 50% of the samples collected were a dendrite form according the basic classification. At the control region 53% of the samples collected were a form of needle and plate according the basic classification. The research Gold & Power conducted supports the research conducted at the coastal and control regions. On comparison the average temperature of the coastal region was generally warmer than the temperature of the control region at 24.7 o F and 21.1 o F respectively. Figure 19 - Temperature and Amount of Crystal Structures: This graph displays variations type and amount of snow crystal formations as a result of change in cloud temperature. (Gold & Power)

22 Spring 2010 ES/PHY 499 SENIOR RESEARCH 21 iii. Valley vs. Coastal Differences in the snow crystal structure between the valley and the coastal locations are evident. By examining the pie charts of the structure distribution for the basic classification (refer to Figure 17b & 17c) a similar situation is present as was for the control versus the coastal regions. The valley site received half as many different types of snow crystal structures than the coastal region. The coastal region maintained to have a much wider spectrum of structures. The valley region received eight different types of snow crystal structures and these types are broken down in Figure 17b. The coastal region received fifteen different types of snow crystal structures (Fig. 17c). Based on observations the snow crystal structures collected at the coastal region are further developed and of greater complexity than the snow crystal structures collected in the valley region. The predominate snow crystal structure collected at the coastal region were stellar dendrites (27%), while the predominate snow crystal structure collected in the valley region were simple needles (31%). For stellar dendrites to form the snow crystal needs to cycle through the cloud until it reaches it critical velocity to fall out of the cloud. Simple needles are formed very quickly within the cloud and require little growth before reaching critical velocity and falling out of the cloud. In comparison of the two locations we can see that the coastal region received doubled the amount of riming than the valley region. Aggregation is more apparent in the coastal region than the valley region as well. Examining the pie charts of the structure distribution for the Magono & Lee classification (Refer to Figure 18b & 18c) we can deduce that both regions received similar patterns in the types of snow crystal structures. The valley region received eight different types of snow crystal structures as seen in Figure 18b. The coastal region received fifteen different types of snow crystal structures and these types are represented in Figure 18c. Observations show that the snow crystal structures collected in the valley and the coastal regions are similar in pattern. In both areas the predominate types of snow crystal structures collected were plane, needle, and rimed. However, the amounts collected within each region varied (refer to Figures 18b & 18c). Both regions collected samples that were rimed. The coastal region received 46.7% rimed snow crystals and the valley region received 26% rimed snow crystals. (Fig. 20) Figure 20 - Riming Percentages: Percentage of rimed samples at each location site for samples observed during Storm 1 on December 31, 2009 and Storm 2 on January 3, The valley collected rimed snow crystals as a result of the topography of the valley acting as a basin, confining the warm air. This warmer layer of the atmosphere can be attributed to an inversion aloft. An inversion can develop aloft as a result of air gradually sinking over a wide area and being warmed by adiabatic compression. This would be classified as a subsidence inversion. Not only can these temperature inversions cause any snow crystals to melt, but they could put a cap on the air over a region.

23 Spring 2010 ES/PHY 499 SENIOR RESEARCH 22 proximity to a body of water, namely Long Island Sound. This body of water keeps the region much warmer with a higher humidity than regions further inland. The average relative humidity of the coastal site was 87%, compared to 82.5% (valley) and 51.5% (control). The addition of a higher humidity results in more water particles being present in the atmosphere at the time of snow crystal formation. As the snow crystals fall there is a larger quantity of water droplets the crystals descend through and collide with causing heavily rimed samples as observed at the coast. Based on the storms during which collection took place, one can deduce that both regions had similar maximum size snow crystals. (Fig. 21c) During Storm 1 the size of the snow crystals collected in the valley region ranged from 1 mm to about 7 mm, with an average of about 3.5 mm. In comparison, the coastal region range from 1 mm to about 5.5 mm, with an average of about 3 mm. (Fig. 21a) During Storm 2 the size of the snow crystals collected in the valley region ranged from 1.9 mm to about 5.5 mm, with an average of about 3 mm. In comparison the coastal region ranged from 1 mm to about 7 mm, with an average of about 3 mm. (Fig. 21b) Overall both regions received a similar range of sizes of snow crystals. b. Role of Aerosols Figure 21 - Size Distribution: Snow crystal size distribution during Storm 1 on December 31, 2009 (fig. 21a), Storm 2 on January 3, 2010 (fig. 21b) and the entire size spectrum for both Storm 1 and Storm 2 (fig. 21c). The reason the coastal region collected rimed snow crystals is mainly due to the area s Aerosols constitute a vital entity in this research. By restricting our data collection to the winter season, the role of aerosols is a control as distribution is constant and unique to a particular area. As a result, these findings presented can be extrapolated to other coastal, valley, and control locations. The sources of aerosols at the coastal location are primarily that of sea salt particulates, while industrial sources distribute aerosols in the control and valley locations. However, unlike the control location, the valley location has a greater concentration of aerosols as they are trapped in the valley. (To note: atmospheric conditions in the winter season are favorable to the development of an inversion

24 Spring 2010 ES/PHY 499 SENIOR RESEARCH 23 layer, which traps the aerosols resulting in higher concentrations at all locations.) The unique distribution of aerosols and particulate types at each location proves to be of significance and is the control on which future research may be based upon. c. Identifying characteristics of locations i. Coastal The coastal region collected 150 snow crystal samples. These samples ranged in size from a minimum size of 0.50 mm and a maximum size of 7.00 mm. The average size of the snow crystals collected in this region was 2.35 mm. According to the basic classification chart the 150 samples divide into fifteen different snow crystal structures. The three most predominate snow crystal structures identified in the coastal region are: Stellar Dendrites (27%), Radiating Dendrites (18%) and Graupel (14%). According to the Magono & Lee classification chart the one hundred and fifty samples divide into five different snow crystal structures. The five snow crystal structures of the coastal region are: Plane (43%), Needle (7%), Rimed (35%), Irregular (13%) and Column (2%) % of the snow crystals collected in the coastal region was rimed. This large amount of riming can be explained by the high moisture content in the atmosphere due to the coastal region s proximity to a body of water. This high moisture content is evident in the weather data that was collected after every twenty-five snow crystals identified with an average relative humidity of 87%. Aggregation was extensive as well at the coastal region. Most of the aggregates observed were radiating dendrites made of two to three crystals. In certain cases some mature aggregates (four or more snow crystals) were observed as well but were unstable in the grouping and broke apart upon impact with the collection surface. ii. Valley The valley region collected one hundred snow crystal samples. These samples ranged in size from a minimum size of 0.90 mm and a maximum size of 7.00 mm. The average size of the snow crystals collected in this region was 3.71 mm. According to the basic classification chart the 100 samples divide into eight different snow crystal structures. The three most predominate snow crystal structures identified in the valley region are: Simple Needle (31%), Stellar Dendrite (20%) and Radiating Dendrite (15%). According to the Magono & Lee classification chart the 100 samples divide into three different snow crystal structures. The three snow crystal structures of the valley region are: Plane (55%), Needle (36%) and Rimed (9%). Rimed samples did not dominate the snow crystals collected in the valley as they did in the coastal region, but this region collected a moderate amount at 26%. The reason for the rimed snow crystals was due to the topographic effect of the valley on the moisture content in the atmosphere over the valley region. Based on the 100 snow crystals identified in the valley region none were recorded to be under the influence of aggregation. iii. Control The control region collected 100 snow crystal samples. These samples ranged in size from a minimum size of 0.55 mm and a maximum size of 6.80 mm. The average size of the snow crystals collected in this region was 3.04 mm. According to the basic classification chart the 100 samples divide into ten different snow crystal structures. The three most predominate snow crystal structures identified in the control region are: Hexagonal Plates

25 Spring 2010 ES/PHY 499 SENIOR RESEARCH 24 (21%), Stellar Dendrites (19%) and Sectored Plates (13%). According to the Magono & Lee classification chart the 100 samples divide into four different snow crystal structures. The four snow crystal structures of the control region are: Plane (80%), Needle (16%), Column (3%) and Irregular (1%). In the control region rimed snow crystal structures were rare at 4% of the snow crystals collected. Aggregation was not observed either as the type of snow fall was light and loosely compacted. This is in accordance with relatively low moisture content at this site. CONCLUSION Conclusive evidence exists of the orographic effect determining snow crystal formation observed at the distinct locations of coastal, valley, and control. Disparities in structure and size were evident with fewer and simpler structures observed at the control location and more complex and varied structures at the coast. The valley location consisted of a balance between the coast and control. Riming and aggregation were also highly influenced by location with a strong presence at the coast, moderate for the valley, and almost negligible for the control. As aerosol dispersion is of uniformity and unique at all location for the winter season, these results may be extrapolated to other regions characterized by the locations analyzed here. IMPLICATIONS FOR FURTHER RESEARCH Recommended research would be the collection and identification of snow crystal formations in other locations similar to the three locations used in our research to provide more evidence to support the orographic effect on snow crystal formations. Also, within each location multiple sampling groups should be present and a greater quantity of snow crystals structures should be recorded to reduce sampling error. Along with weather data, cloud temperatures as well as the amount and type of particulates present in each region should also be recorded. The research conducted here lends itself to a multitude of further investigations that are highly encouraged. ACKNOWLEDGEMENTS This research would not have been possible without the advisement and expertise of Albert Owino Ph. D., professor of meteorology, PAM Department Chair, and Director of the Weather Center at Western Connecticut State University. Also, many thanks to the other professors of the PAM Department at Western Connecticut State University for their suggestions and support including Alice Chance, Ph.D., professor of physics, James Boyle, Ph.D., professor of meteorology, and Dennis Dawson, Ph. D., professor of astronomy. Thank you to Steven R. Schmidt for his editorial expertise and advice as well as Zachariah Silver for his continued support. Our sincere thanks and gratitude to all. REFERENCES Bentley, W. A. (1922). Photographing Snowflakes. Popular Mechanics, 37, Bentley, W. A. (1910). Snow Beauties. Technical World. Gold, L. W., & Power, B. A. (1952, December). Correlation of snow-crystal type with estimated temperature of formation. Correspondence, 447. HPC Daily Forecast Map Archive. (n.d.). Hydrometeorological Prediction Center (HPC) Home Page. Retrieved February 5, 2010, from HPC Daily Forecast Map Archive. (n.d.). Hydrometeorological Prediction Center (HPC) Home Page. Retrieved February

26 Spring 2010 ES/PHY 499 SENIOR RESEARCH 25 28, 2010, from noaa_archive.php. Libbrecht, K. (2006). Ken Libbrecht's Field Guide to Snowflakes. St. Paul: Voyageur Press. Magono, C., & Lee, C. W. (1966). Meteorological Classification of Natural Snow Crystals. Journal of the Faculty of Science: Geophysics, Hokkaido University, 2 (4), Peterson, T. C., Yeh, J.-D., & Cotton, W. R. (n.d.). Manual for Snowflake Observation, Identification, and Replication. Fort,Collins, Colorado: Colorado State University Department of Atmospheric Science. Relative Humidity (n.d.). Wikipedia the Free Encyclopedia. Retrieved March 3, 2010, from Relative_humidity. USGS Map Locator. (2009, December 19). Retrieved February 28, 2010, from The USGS Store: maplocator Walk, A.M. (n.d.). Cloud Physics: Collision, Coalescence, the Bergeron Process. College of Dupage Next Generation Weather Lab. Retrieved March 14, 2010, from Wallace, J. M., & Hobbs, P. V. (2006). Atmospheric Science: An Introductory Survey (2nd ed.). New York: Academic Press. Cover Page: Photograph taken by Annie Palumbo at Weston, CT (Coastal location).

27 APPENDIX A PROPOSAL, COLLECTION TEMPLATES & CHARTS Research Proposal Spring 2010 ES/PHY 499 Senior Research 4 cr. MTR 450 Senior Research in Meteorology 4 cr. Annie Palumbo and Ryan Suter Paul Shupenis Topic: Orographic Effect on Snow Crystal Structure Advisor: Dr. Albert Owino Statement of Proposed Research By collecting multiple snow crystal samples over several trial storms at three distinct locations and analyzing the characteristics of the snow crystals, we will determine the effect of orographic location upon snow crystal structure. The three locations will be a coastal, valley, and control locations in mid and southeastern Connecticut. Snow crystals will be collected on a chilled black surface and analyzed with a 10x magnification loupe as Bentley devised in his research. The structure of the snow crystals will be recorded and classified according to a basic classification scheme arranged by Libbrecht and the more complex Magono and Lee classification. Weather data will also be recorded for every 25 samples to take the shift of the storm over time into account. Weather information will be recorded utilizing Weather Underground s continuous local updates. Analysis will be done through a series of data tables, charts, and graphic visuals. A discussion will also analyze the snow crystal structure for each location and compare to the other locations. Hypothesis If snow crystals are collected at various orographic locations then the location will be a determining factor in the production of the snowflake s crystalline structure characteristics. Questions to Answer 1. Does location have an effect on the crystalline structure of snowflakes? 2. Does a particular crystalline structure predominate at a given orographic location? 3. Does the type and duration of the storm effect growth and quantity of snowflake crystalline structure? Goal The goal of this research is to formulate questions that can be explored by scientific investigations, articulate a testable hypothesis, design investigations to explore natural phenomena, perform investigations to explore natural phenomena, organize and analyze data, interpret data and draw conclusions, and assess the validity of the conclusions. Emphasis will be placed on introducing the student to meteorological research, peer-reviewed

28 journals, current research methods and topics, data analysis and interpretation, and effective communication of project results. This research will be assessed by: And either: A. A written research paper (required) Assessment A. In accordance with the Performance Standards for Scientific Inquiry utilizing the Scoring Rubric for Science Inquiry (ES/PHY 499 Students) B. Oral defense of the research carried out (MTR 450 Students) Methodology and Strategy The methodology will be primarily derived from the work of Bentley, Libbrecht, Magono and Lee. Bentley used the method of collecting snow crystals on a chilled blackboard and analyzing with a magnifying glass in order to select snow crystals for his photography. Initial planning was to collect snow crystals on glass slides through an acrylic replica method and photograph each slide; however this proved to be unsuccessful as the sampling error would be far larger due to collection limitations. Therefore recording of snow crystal structure and size is to be done in the field prior to melting. Rather than using a blackboard, laminated collectors have been created. The first classification is derived from Libbrecht s basic classification of snow crystals, as outlined in his Field Guide to Snowflakes. Magono and Lee s classification system, which is considered the official classification system by meteorologists, will constitute the second detailed classification. Further procedure is outlined as follows: Collection Locations Data will be collected among three joint experiments at three separate locations. 1. Southbury, CT Control Ryan Suter 2. Naugatuck, CT Valley Paul Shupenis 3. Weston, CT Coastal Annie Palumbo Weather Data Weather data will include but is not limited to the following variables: o Storm characteristics o Surface temperature o Surface wind chill o Relative Humidity

29 o Surface dew point o Wind speed and direction o Pressure o Visibility o Cloud Elevation o Size of snow crystal

30 14. Contact group about upcoming storm. Collection Procedure 15. Place laminated Field Collection Chart, Snow Crystal Collector, and Magono & Lee Snowflake Classification System outside to chill along with a writing utensil and loupe. (You may wish to keep these in your freezer.) 16. Begin to fill out Official Collection document electronically concerning the current weather conditions right before beginning collection. 17. Go outside to collect snowflakes on collector. 18. Examine each snow crystal quickly prior to melting. (This is easiest under some type of overhang outside, like a porch. Try not to breathe on the snow crystal.) 19. Record basic classification number, Magono & Lee classification number, whether or not there is riming, the size, and any other observations as time permits. 20. Collect at least 50 crystals per snow event, up to 200 samples if possible. 21. Wipe Field collection chart clean to prepare for next collection. 22. Go inside and transfer data to official electronic copy listing both the number and full classification name. 23. Complete analysis section of Official Collection document. (Edit data tables as needed.) 24. results to group. Relevance and Importance to Modern Atmospheric Science Conducting this research in the scope of modern atmospheric science allows the opportunity to analyze determinant factors in the variance in snow crystal structure. The recording of weather data and analysis thereof serves the purpose of conducting further analysis as to why snow crystal structure differs orographically. Past research has focused on categorizing snow crystal structure and formation, but not on the difference in crystalline structure based on coastal and valley topographic locations. If structure does in fact differ between these locations, we will seek to analyze the atmospheric attributes responsible.

31

32 Field Collection Chart Sample # 1 Basic Classification Magono & Lee Classification Riming Size (mm) Other Observations

33 Sample # 26 Basic Classification Magono & Lee Classification Riming Size (mm) Other Observations

34 Sample # 51 Basic Classification Magono & Lee Classification Riming Size (mm) Other Observations

35 Sample # 76 Basic Classification Magono & Lee Classification Riming Size (mm) Other Observations

36 Place black construction paper here and laminate Types of Snowflakes Snow Crystal Collector

37