Aim: What are the major layers of the atmosphere?

I. Atmosphere : - is the layer of gases surrounding the Earth.

II. Pressure Changes - Atmospheric pressure is simply the weight of the air above. - Measured with a barometer

- The atmosphere thins as you travel away from Earth’s surface until there are too few gas molecules to detect. - At sea level there is 1 atm. (atmosphere) of pressure. All the air above your head creates this pressure. Where would you expect to find the most pressure? Where would you expect to find the least pressure? At sea level (1 atm) On a mountain peak

-Pressure is highest at sea level = 1.0 atm. -As altitude increases air pressure decreases. -At the top of the Stratosphere the pressure comes close to 0 atm. Why does the pressure approach zero as altitude increases? Think about what causes air pressure - A decrease in air molecules ESRT page 14 Sea level

ESRT ESRT Page 13

III. Layers of the Atmosphere

1.Troposphere: (where we live!) –90% of all gases –all clouds and weather –Temp. decreases as altitude increases What is the lowest temperature in the Troposphere? C

2. Stratosphere: –Contains Ozone Layer which blocks dangerous ultraviolet radiation. –Temperature increases as altitude increases. What is the highest temperature in the stratosphere? 00C00C

–Contains Jet Streams; which are high speed winds that influence our daily weather.

3. Mesosphere –Meteoroids burn up due to friction with air particles forming “shooting stars”. –Temp. decreases as altitude increases. At what altitude does the Mesosphere begin? 30mi or 50km

4. Thermosphere –Temperature increases as altitude increases. –The Ionosphere influences radio communication. - Contains “Aurora’s” or The Northern & Southern Lights

Aurora (Northern Lights)

5. Exosphere Is the uppermost layer of the atmosphere. Contains Earth’s Satellites

* Between each layer is a “pause” or boundary that separates the layers.

ESRT page 14

Closure: - Take out the worksheet that says “Changes in atmospheric Composition” Use your ESRT and notes to answer the questions. You should skip # 7