24.1 The Atmosphere

1. Define the atmosphere…

2. What molecule has the highest concentration in the atmosphere? ( oxygen, Carbon dioxide, nitrogen?)

3. Why is the atmosphere important? (3 things)

• The atmosphere is … the layer of gases that surround the earth

The Function of the Atmosphere:

a. Holds Heat and helps moderate Earth’s temperatures

b. Provides Protection from …1. Meteoroids2. High Energy Radiation (UV rays) from the sun

c. Provides gasses essential for life – Oxygen – Carbon dioxide – Nitrogen

Composition of the Atmosphere a. Nitrogen (78%), oxygen (21%), other gases and water vapor (1%) b. Suspended Solid and liquid particles Ash and smoke from fires or volcanoes – Salt from ocean spray

OZONE LAYER a. Ozone in Troposphere = “Bad” ozone

1. Acts as greenhouse gas (traps heat) and causes smog.

b. Ozone in Stratosphere= “Good” ozone1. Made of O3 molecules

2. absorbs UV rays that can be harmful to plants and animals3. UV radiation is Thermal Energy which warms strato.

c. OZONE HOLE = Thinning of ozone layer 1. Where: over poles2. Cause: chemicals, CFCs (Chloroflourocarbons), used as coolants in refrigeration and aerosols, get into atmosphere and break apart ozone molecule … allowing more UV in.

Air Pressure: the force on a surface due to the weight of air

a. The atmosphere has weight because of gravity

b. As altitude increases, air pressure and density decreases c. Measured with a barometer

Layers of the Atmosphere• Troposphere:

1. 0-12km (~ 7 mi)2. Weather & Clouds3. Greatest air pressure & density (Gravity pulls air to surface)4. Temp. DECREASES with altitude (As air expands it cools)

Stratosphere1. 12 km – 50 km (~ 32 mi)2. Contains ozone layer3. Temperatures WARM from -57C to 0C.4. Upper strat. is warmer than lower b/c of OZONE LAYER which is absorbing UV radiation

http://www.youtube.com/watch?v=FHtvDA0W34I

Mesosphere 1. 50-80 km (~52 mi),2. Temps decrease as altitude increases3. Top of Meso. Is - 90 C4. Very thin air – moving VERY FAST. Windy (320 km/hr).5. This burns up meteoroids

Thermosphere 1. OUTER MOST LAYER2. 80 km – outer space3. TEMP INCREASES w/ Alititude. ( - 90 C to more than 1000 C)4. Temps. Increase because gas molecules in this layer absorb solar radiation

Ionosphere1. Part of

THERMOSPHERE2. Region of charged

particles (ions) that overlaps the lower thermoshere.

3. Molecules absorb solar energy and b/cm (+) charged or IONS.

4. Aurora – Charged particles are attracted to E’s mag. Poles – collide w/ ions & glow