1. Atmosphere

2. Atmosphere Composition: Gases - nitrogen, oxygen, argon, other gases Compounds – carbon dioxide, water vapor

3. Atmospheric pressure – Gravity pulling the gases of the atmosphere towards the earth’s surface. Barometer – Instrument that measures atmospheric pressure. Ex. – mercury barometer Standard atmospheric pressure – average atmospheric pressure at sea level. (29.92)

4. Mercury Barometer

5. Layers of the Atmosphere (Troposphere) Troposphere – layer closest to the earth’s surface. - Almost all the water vapor and carbon dioxide is found in this layer. - Temperature decreases at 6.5°C/km until you reach 10km, where is stops decreasing. - Tropopause – the upper boundary of the troposphere, where the temp decrease stops.

6. Stratosphere Stratosphere – Extends upward to an altitude of 50km. - Contains almost all the Ozone (O 3 ) - Stratopause – Marks the upper end of the stratosphere

7. Mesosphere Mesosphere – extends to an altitude of 80 km. - the coldest layer of the atmosphere (-90°C) - Mesopause – upper boundary of the mesosphere.

8. Thermosphere Thermosphere – the upper layer of our atmosphere. - the air is very thin, cannot be measured with a regular thermometer. - Ionosphere - the lower region of the thermosphere. - Exosphere – above the thermosphere where the earth’s atmosphere blends in with space.