Chapter 1 The Atmosphere
Section 1 - Guiding Questions How is the atmosphere important to living things? What gases are present in Earth s atmosphere?
Section 1 - The Air Around You Importance of the Atmosphere Weather the condition of Earth s atmosphere at a particular time and place The weather today in Nampa will be different that it will be in New York City. Atmosphere the layer of gases that surrounds the planet Apple example
Earth s atmosphere makes conditions on Earth suitable for living things Contains oxygen and other gases that you and other living things need to live. Living things affect the atmosphere. Provides warmth and liquid water living things need to survive. Protects living things from radiation and meteoroids from outer space.
Question: What would conditions on Earth be like without the atmosphere?
Composition of the Atmosphere Earth s atmosphere is made up of: Nitrogen Oxygen Carbon dioxide Water vapor Other gases Particles of liquids and solids
Gases in the Atmosphere OTHER GASSES % BY VOLUME
Gases in the Atmosphere
Nitrogen Nitrogen is essential for all living things. Most living things cannot take nitrogen directly from the air. It needs to be converted by plants to nitrates then to proteins. Video
Oxygen Oxygen is also needed by living things. Plants and animals can take this gas directly from the air and use it to release energy from food in a usable form Video All fuels use oxygen to burn which uses up oxygen rapidly Ex. Cars, candles, campfire, etc. During other processes, oxygen is used up slowly. Ex. Rusting
Carbon Dioxide Carbon dioxide is essential for life. Plants need carbon dioxide to produce food. Animals need oxygen to produce food. Thus each gives off the opposite as waste.
Fuels like coal and gasoline give off CO 2 thus increasing the levels of CO 2 in the atmosphere. Rising CO 2 levels in the atmosphere may be raising the temperature of the Earth. Global Warming Video
Everything else Water vapor is H 2 O in the form of a gas. It is invisible. The amount of water vapor varies from place to place and time to time. Ex. Desert vs. rain forest Particles in the atmosphere might be: Dust Smoke Salt
Review Questions 1. Describe two ways in which the atmosphere is important to life on Earth. 2. What are the four most common gases in dry air? 3. How would the amount of carbon dioxide in the atmosphere change if there were no plants? If there were no animals?
Section 1 - Guiding Questions How is the atmosphere important to living things? What gases are present in Earth s atmosphere?
Section 3 - Guiding Questions What are some of the properties of air? What instruments are used to measure air pressure? How does increasing altitude affect air pressure and density?
Section 3- Air Pressure Properties of Air Since air has mass, it also has other properties like density and pressure. Density = Mass/Volume If there are more molecules in a given volume of air, the density is greater. Molecules Density If there are fewer molecules, the density decreases. Molecules Density Pressure the force pushing on an area or surface. If a substance is more dense, then it has more molecules per unit of volume and exerts more pressure. Ex full backpack vs. empty backpack
Air pressure the result of the weight of a column of air pushing down on an area. Ex. - The air pressure on your desk. Video Video
Measuring Air Pressure Barometer is an instrument that is used to measure changes in the air pressure. There are two kinds of barometers: Mercury Aneroid
Mercury Barometers A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. The space at the top has no air, it s a vacuum. The bottom end is placed in a bowl of mercury. When air pressure increases, it pushes down more on the surface of the mercury forcing the mercury higher. Video
Aneroid Barometers Aneroid barometer has an air tight metal chamber. The metal chamber is sensitive to changes in air pressure. When air pressure increases the walls of the chamber are pushed in. When it decreases, they bulge out.
The walls are connected to springs and dials that measure the pressure. These barometers are smaller and do not contain any liquid. As the shape of the chamber changes, the needle on the dial moves. Video
The Units Most weather reports use inches of mercury. Ex. The barometer is about 30 inches National Weather Service maps indicate air pressure in millibars. 30 inches of mercury is approximately equal to 1,016 millibars
Question: Name two common units used to measure air pressure.
Increasing Altitude Altitude, or elevation, is the distance above sea level which is the average level of the surface of the oceans. Air pressure decreases as altitude increases. As air pressure decreases, so does density. EX: stack of books
As you go up in the atmosphere, air pressure decreases so density decreases as altitude increases. There are fewer oxygen molecules available to breathe.
Review Questions How does increasing the density of a gas affect its pressure? Describe how a mercury barometer measures air pressure. Why is the air at the top of a mountain hard to breathe? What changes in air pressure would you expect to see if you carried a barometer down into an underground cave? Explain.
Section 3 - Guiding Questions What are some of the properties of air? What instruments are used to measure air pressure? How does increasing altitude affect air pressure and density?
Section 4 - Guiding Question What are the characteristics of the main layers of the atmosphere?
Section 4 Layers of the Atmosphere There are 4 layers of the atmosphere: Troposphere Stratosphere Mesosphere Thermosphere Video
Troposphere Tropo turning or changing; conditions in this layer are more variable than the other layers 0-16 km above the equator. The troposphere is where the Earth s weather occurs. As the altitude increases, temperature decreases. For each 1km in altitude, temp. goes down 6.5 o C until reaching -60 o C. Weather balloons
Stratosphere Strato layer or spreading out. 16-50km above the equator. The lower part is about -60 o C while the upper part is warmer, about -20 o C. This is because of the ozone layer. Ozone is the 3-atom form of oxygen, which absorbs energy from the sun and then converts it into heat. The ozone layer also protects us from the sun s ultraviolet radiation.
Mesosphere Meso middle 50-80km above the equator. The layer is the coldest, -90 o C. It protects the Earth from most meteoroids, what you see is as a shooting star is a trail of hot, glowing gases the burning meteoroid leaves behind. Checkpoint: What is the depth of the mesosphere?
Thermosphere Thermo heat 80+km. The air is very thin, about.001% than that of sea level. Temperatures reach 1,800 o C yet a thermometer will show below 0 o C. Temperature is the measure of the motion of energy of the molecules. Video
Thermosphere The thermosphere has two parts: Ionosphere - 80-550km where the aurora borealis (Northern Lights) takes place Exosphere 550+ km where phone and TV signals send signals to satellites
Review Questions Describe one characteristic of each of the four main layers of the atmosphere. What is a shooting star? In which layer of the atmosphere would you see it? What if the aurora borealis? In which layer of the atmosphere does it occur? Why is the mesosphere the coldest part of the atmosphere?
Section 4 - Guiding Question What are the characteristics of the main layers of the atmosphere?