1. The Atmosphere BIG IDEAS: Earth’s atmosphere is a mixture of gases that moves heat and allows life to exist on Earth.
Weather patterns are created from interactions among ocean currents, air masses & topography.

2. Purposes of our atmosphere:
breathing (oxygen)– (You can survive for a few days without food or water but less than 5 minutes without the oxygen)
protects us from harmful solar rays (like UV and gamma)
warmth (traps heat)
water/water vapor
protection from most
meteoroids

3. What makes up air?

4. What makes up DRY air? 78% nitrogen--used to make protein
21% oxygen (from photosynthesis)—processes that use oxygen:
cellular respiration (plants and animals)
oxidation (like rust, tarnish)
combustion (burning)
--1% other gases (argon,
carbon dioxide, other)

5. Air also contains… human pollution (smog, etc)
natural pollution: dust, volcanic ash, sea salt, dirt, pollen, smoke from forest fires
water vapor--amount varies 0-4% (humidity) ~ invisible gas
liquid water (cloud droplets and rain)
solid water (ice and snow)

6. Layers of the Atmosphere 1
The troposphere is the layer closest to Earth's surface. It is 7 to 20 km thick, and contains half of Earth's atmosphere. Air is warmer near the ground and gets colder higher up. Earth’s weather occurs in the troposphere. Nearly all of the water vapor and dust in the atmosphere are in this layer and that is why clouds are found here. Average temperatures range from 17°C(62°F) to -51°C(-60°F). Temperatures decrease as you go higher.

7. Layers of the Atmosphere 2
The stratosphere is the second layer. It starts above the troposphere and ends about 50km above ground. Ozone is abundant here, it heats the atmosphere while also absorbing harmful radiation from the sun. There is a hole in the ozone layer over Antarctica. Air in the stratosphere is very dry, and it is about 1000 times thinner here than it is at sea level. Because of that, this is where jet aircraft and weather balloons fly.

8. Layers of the Atmosphere 3
The mesosphere starts at 50km and extends to 85km high. The top of the mesosphere, called the mesopause, is the coldest part of Earth's atmosphere, with temperatures averaging about -90C(-130°F) meteors burn up in this layer.

9. Layers of the Atmosphere 4
The thermosphere extends from about 90km to between 500 and 1,000km. Temperatures increase as you go up and can get up to 1,500°C(2,700°F) at this altitude. The thermosphere is considered part of Earth's atmosphere, but air density is so low that most of this layer is what is normally thought of as outer space. This is where the ionosphere is found, space shuttles fly, and the International Space Station orbits Earth. The auroras also occur in the thermosphere.

10. The Ionosphere
The ionosphere is located within the thermosphere. The ionosphere gets its name because nitrogen and oxygen molecules are ionized by solar radiation. In the process of ionization, the neutrally-charged molecules absorb high-energy, short-wavelength energy from the Sun. This causes the molecules to lose one or more electrons and become positively-charged ions. The freed electrons travel within the ionosphere as electric currents.

11. Layers of the Atmosphere 5
The exosphere, the highest layer, is extremely thin & is where the atmosphere merges into outer space. It is composed of very widely dispersed particles of H & He.