Fluid Circulation (Student Mastery Objectives) -The most frequent type of heat transfer of energy in the atmosphere is convection. -Differences in density affect the circulation of fluids. Cold air is denser than warm air and sinks as in the center of a high pressure air mass. Warm air is less dense than cold air and rises as in the center of a low pressure air mass. Cold water is denser than warm water and sinks. Warm water is less dense than cold water and rises. -In the atmosphere, warmer air flows faster and has a lower pressure. In the atmosphere, cooler air flows slower and has a higher pressure. Wind is created when air masses with different air pressures collide. The greater the range in pressures between the two air masses creates faster winds. -As altitude increases, air pressure decreases. As altitude decreases, air pressure increases.
-High pressure air masses flow towards Low Pressure air masses. (Remember the egg that was pushed into the bottle by the higher pressure.) -Increased solar energy in the atmosphere allows for increased amounts of evaporation and precipitation. Decreasing amounts of solar energy allows for cooler air temperatures, less evaporation and precipitation. Increasing amounts of solar energy allows for faster air molecules, lower air pressure and an increased chance for instability (storms). -Tropical areas average 6 centimeters of rain per month. Arid (Dry) Deserts average less than 25 centimeters of rain per year. Loiederman M. School is Temperate Continental with moderate precipitation year round. -Generally, the air temperature above the ocean surface mirrors the water temperature directly below it. -Ocean water at the surface is warmer and driven by wind currents. -El Nino is a cyclical current which warms the normally cooler East Pacific Current and the air above it. El Nino can occur every 2-7 years. El Nino changes weather patterns and climates. El Nino can create severe weather conditions like heavy rains or drought for areas affected. El Nino lasts between 1-2 years.
La Nina is a cyclical current which causes even cooler than normal cool currents in the East Pacific current and the air above it. La Nina can cause colder than normal winters and greater precipitation to the Pacific Northwest and North Central United States. La Nina can cause greater hurricane activity in the Eastern Atlantic Ocean region. -Ocean currents are less dense and warmer at the surface. Deep ocean currents or Thermohaline currents are driven by density and temperature. Their currents are salty and very cold. -The Coriolis Effect causes ocean currents in the Northern Hemisphere to circulate in a clockwise direction. The Coriolis Effect causes ocean currents in the Southern Hemisphere to move in a counter clockwise direction. -Land absorbs solar energy faster than ocean water (Heating Earth s Surface Lab) During the nighttime, land radiates more energy back into the atmosphere than water (The energy reflected from the land is in the form of Infrared Radiation which heats the atmosphere.). Water retains solar energy longer than land. Oceans retain larger amounts of latent or hidden heat.
-During the day, a sandy beach becomes hot and a Low Pressure air mass forms. During the day, the ocean water is cooler than the hot air over the beach and a High Pressure air mass forms. Typically, during the day, a Sea Breeze occurs because the High Pressure air mass flows towards toward the Low Pressure Air Mass. At night, the sandy beach cools quickly and a High pressure air mass forms. At night, the ocean water retains or holds on to heat and the air above it is warmer than the cooled sandy beach. At night a Low Pressure air mass forms over the warmer ocean water. At night, a Land Breeze forms because the High Pressure air mass flows towards the Low pressure Air mass. -Seasons on Earth are caused by the Earth s 23.5 degree tilt on its axis. -Seasonal changes are increasingly evident the farther North and South of the Equator. At the equator, seasonal change is less evident. Loiederman is mid-latitudinal. At this location, the sun appears highest in the sky during the summer months and appears lowest in the sky during the winter months. Daylight is longer in our summer months. Nightlight is longer in our winter months
Fall and Spring months share approximately the same amount of daylight and nightlight hours and minutes. Seasonal change (cont.) The Sunrise in the Eastern sky changes location daily as well as sunset locations in the western horizon. Therefore, the daily amount of sunlight changes each day of the year. Daily amounts of insolation change each day for areas along lines of latitude both North and south of the Equator. -The longer the Sun appears in the sky during the day, the warmer the climate. When the Sun appears less in the sky during the day, the climate is cooler. -Land heats faster than water during the daytime. At night, land cools faster than water. Water retains heat for longer periods than land.