By: Brian C. Bradshaw

1. Atmosphere By: Brian C. Bradshaw

2. Layers of the Atmosphere • Exosphere • Thermosphere • Mesosphere • Stratosphere • Troposphere

3. Troposphere • Starts at earth’s surface and goes 8 to 14.5 kilometers (5-9 miles) • Most dense • As you go higher, temperature drops about 17 to 52 degrees Celsius • Almost all weather is found in this region • Also known as the lower atmosphere

4. Stratosphere • Starts above troposphere and goes 50 kilometers • Dry and less dense than troposphere • Temperature increases gradually to -3 degrees Celsius, due to absorption of ultraviolet radiation • Ozone is in this layer, it absorbs and scatters the solar ultraviolet radiation • 99% of “air” is located in the troposphere and stratosphere • Stratopause separates troposphere and stratosphere

5. Mesosphere • Starts just above the stratosphere and continues for 85 kilometers (53 miles) • Temperatures fall as low as -93 degrees Celsius as you increase in altitude • Chemicals are in excited state as they absorb energy from the sun • Mesopause separates mesosphere from thermosphere • Stratosphere + Mesosphere = middle atmosphere

6. Thermosphere • The thermosphere starts just above the mesosphere and extends to 600 kilometers (372 miles) high. • Temperatures can go as high as 1,727 degrees Celsius. • Chemical reactions occur much faster than on the earth’s surface • Also known as the upper atmosphere

7. Exosphere • This is beyond the atmosphere • Starts at the top of the thermosphere and continues until it merges with the interplanetary gases, or space. • In this region of the atmosphere, Hydrogen and Helium are the prime components and are only present at extremely low densities.