15.1 THE ATMOSPHERE

The Water Cycle Continues

Learning Targets

1. Describe the importance of the atmosphere to our planet and its life

2. Outline the role of the atmosphere in the water cycle

3. List the major components of the atmosphere and know their functions

4. Describe how atmospheric pressure changes with altitude

Significance of the Atmosphere #1

1.Provides the gases needed for life

2. Moves watera) Clouds and water vapor

3. Absorbs solar energya) Ozone layer

4. Regulates temperaturesa) Greenhouse effect

5. Transmits energya) Allows for sound

Photosynthesis

1. Plants turn CO2 and H2O into sugar and O2

2. Plant sugars are the basis for all food chains

3. Put nearly ALL OXYGEN into the atmosphere

Respiration

1. All plants and animals need oxygen

2. Organisms turn O2 and sugar into energy, CO2, and water

3. Releases energy stored during photosynthesis

Significance of the Atmosphere #2

1. Provides the gases needed for life2.Moves water

a)Clouds and water vapor

3. Absorbs solar energya) Ozone layer

4. Regulates temperaturesa) Greenhouse effect

5. Transmits energya) Allows for sound

Significance of the Atmosphere #2

1. Water spends about 9 days in the atmosphere as water vapor.

2. ALL weather takes place in the atmosphere

a) Weather – describes what the atmosphere is like at a specific time and place

i. Includes – temperature, wind, precipitation

b) Climate – long-term average of weather in a particular location

Significance of the Atmosphere #3

1. Provides the gases needed for life2. Moves water

a) Clouds and water vapor

3.Absorbs solar energya)Ozone layer

4. Regulates temperaturesa) Greenhouse effect

5. Transmits energya) Allows for sound

Significance of the Atmosphere #3

1. Ozone – molecule composed of three oxygen atoms - O3

2. Absorbs Ultraviolet (UV) radiation a) Protects life

Significance of the Atmosphere #4

1. Provides the gases needed for life2. Moves water

a) Clouds and water vapor

3. Absorbs solar energya) Ozone layer

4.Regulates temperaturesa)Greenhouse effect

5. Transmits energya) Allows for sound

Significance of the Atmosphere #4

1. Keeps Earth within an acceptable temperature range

2. Greenhouse gases trap heat in the atmosphere to help moderate global temperatures

a) Carbon Dioxideb) Methanec) Water vapord) Ozone

Significance of the Atmosphere #5

1. Provides the gases needed for life2. Moves water

a) Clouds and water vapor

3. Absorbs solar energya) Ozone layer

4. Regulates temperaturesa) Greenhouse effect

5.Transmits energya)Allows for sound

Significance of the Atmosphere #5

1. Gases in the atmosphere takes up space and provides collisions to occur

2. Without an atmosphere:a) No sound – Why?

i. No collisions of moleculesb) Airplanes cannot fly – Why?

i. No atmosphere to hold it up

Composition of Air

1. Major gas componentsa) Nitrogen: 78%b) Oxygen: 21%c) Argon: 0.9%d) Other: 0.1%

2. Also contains particles that allow water vapor to condensate on:

a) Water, soil, smoke – Condensation nuclei

Composition of Air

1. Humidity – amount of water vapor in the air

2. Humidity varies around the worlda) Higher humidity at equatorial regions

i. Warm air holds more moisture than cooler air.

b) Lower humidity at polar regions – lower temperatures

Components of the Atmosphere

1. Altitude – atmosphere has different properties at different elevations

2. Density – number of molecules in a given volume

Components of the Atmosphere

1. Air density decrease with altitude – Why?

a) Gravity pulls gas molecules towards Earth’s center

b) Air is denser at sea level where gravitational pull is greater

i. Air piles up close to the earth’s surface

Components of the Atmosphere

1. Air (atmospheric) pressure – force of air weighing down over a unit of area

Components of the Atmosphere

1. What about the composition of air as altitude increases?

2. Major gas componentsa) Nitrogen: 78%b) Oxygen: 21%c) Argon: 0.9%d) Other: 0.1%

3. Composition stays the same with one exception – at 20- 40 km above the surface, there is a greater concentration of ozone molecules

Movement of Air

1. Hot air takes up more spacea) Less dense risesb) Hot means moving faster

2. What is the most important way heat moves around in the atmosphere?

Convection!