Why do you think people are so interested in learning about Earth’s atmosphere? Daily Challenge, 11/1

Think about air pressure and watch the demonstration today. Explain WHAT happens and WHY it happens. Use sketches to help your explanation. Daily Challenge, 11/2

The class will work with a computer model about air pressure. Think about what you learn and how it explains the egg-in-a-bottle demonstration. How does your explanation in yesterday’s challenge compare to what really happens. Explain similarities/differences. Daily Challenge, 11/3 Air Pressure AppletEgg Bottle Video

Probably originated from degassing of planet through volcanoes, perhaps some early comet impacts Early composition: N 2, CO 2, H 2 O, SO 2 Primitive aquatic organisms breakdown CO 2 and SO 2 and produce O 2 as a waste product (long time to build up) Much of the early O 2 was converted to O 3 (which is ozone!) by solar radiation Where did the earth’s atmosphere come from?

So what is the earth’s atmosphere made of today? 78% N 2 (nitrogen) 21% O 2 (oxygen) 0.9% Ar(argon) 0.03%CO 2 (carbon dioxide) 0-5%H 2 O(water vapor) tiny amounts of other gasses –methane, CFC’s, N 2 O, S 2 O, other air pollutants particles –dust, ash, sea salt, smoke, etc.

How does air pressure change with altitude? The further you get from earth’s surface, the lower the air pressure. – Gravity causes this. – The air at any altitude has the weight of all the overlying air pressing down on it. Air Pressure Appletegg bottle video

Think about the air pressure computer simulation we played with yesterday. Low pressure is usually associated with windy, cloudy, stormy weather. WHY do you think this is true? Daily Challenge, 11/4

29.6 inches Hg 30.1 inches Hg 29.4 inches Hg 29.8 inches Hg

How does air temperature change with altitude? As altitude increases, the temperature decreases for the first 12 km above the surface. –Surface of earth absorbs light, converts it to heat. Heat is “trapped” by greenhouse gasses like H 2 O, CO 2, CH 4. From km it gets warmer with increased altitude. –Ozone layer absorbs uv radiation, turns it to heat. From km it gets colder with increased altitude. –few things to absorb light and turn it into heat Above 90 km it gets warmer with increased altitude. –Thin gasses are ionized by intense solar radiation.

EXOSPHERE –Upper part of thermosphere merges with empty space THERMOSPHERE –“hottest” layer, ionosphere, space shuttle/station MESOSPHERE –coldest layer, some ionosphere & meteorites at top STRATOSPHERE –contains ozone layer TROPOSPHERE –90% of atmosphere is here, weather here Earth’s Atmosphere Layers