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The Earth’s Atmosphere

The Earth’s Atmosphere. Overview of the Earth’s atmosphere Vertical structure of the atmosphere. Early Atmosphere.

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The Earth’s Atmosphere

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  1. The Earth’s Atmosphere • Overview of the Earth’s atmosphere • Vertical structure of the atmosphere

  2. Early Atmosphere • The evolution of life and the atmosphere are closely linked – 4 billion years ago ancestors of green plants produced the oxygen (photosynthesis) and cycles the carbon (e.g. limestone) -These early organisms began to change the Earth’s atmosphere slowly, but drastically! • Oxidized modern atmosphere (N2, O2, CO2, etc.)

  3. Overview of the Earth’s Atmosphere • The atmosphere, when scaled to the size of an apple, is no thicker than the skin on an apple. • Atmosphere: • 1.The envelope of gases surrounding the earth or another planet: Nitrogen, oxygen, helium, neon, argon, water vapor, and other substances. • 2. This is the mixture that we call “air.”

  4. Composition of the Atmosphere • The “dry atmosphere”: 78% N2, 21% O2, 1% Ar • N2 is primordial – it’s been part of the atmosphere as long as there’s been an atmosphere • O2 has been rising from none at all about 2.2 Gya – comes from photosynthesis

  5. Layers of the Atmosphere • vertical temperature (T) profile • troposphere • stratosphere • mesosphere • thermosphere • Temperatures, winds, humidity and pressures high above the ground are measured twice-daily by radiosonde.

  6. Troposphere • This layer contains the weather • Tropopause-

  7. Stratosphere • This layer sits on top of the troposphere • It’s elevation ranges from 10 km to around 25 km • This layer contains the ozone layer, which protects us from harmful sunlight

  8. Mesosphere

  9. Thermosphere • This is the highest layer of the atmosphere • It’s height ranges from 100 to 400 km • This is where most small meteorites burn up and is also the location in the atmosphere that the northern lights occur (aurora borealis)

  10. Lapse Rate • The rate at which air temperature decreases with height. • The standard (average) lapse rate in the lower atmosphere is about 6.5°C per 1 km or 3.6°F per 1000 ft.

  11. Temperature Inversion • An increase in air temperature with height often called simply an inversion.

  12. Layers Troposphere – Temp decrease w/ height Most of our weather occurs in this layer Varies in height around the globe, but Averages about 11 km in height.

  13. Layers Stratosphere- Temperature inversion in stratosphere Ozone plays a major part in heating the air at this altitude

  14. Layers Mesosphere- Middle atmosphere – Air thin, pressure low, Need oxygen to live in this region. Air quite Cold -90°C (-130°F) near the top of mesosphere

  15. Layers Thermosphere “Hot layer” – oxygen molecules absorb energy from solar Rays warming the air. Very few atoms and molecules in this Region.

  16. Temperature in atmospheric layers • The troposphere is warmed primarily by the Earth’s surface; temperature decreases as altitude increases in this layer. • Temperatures increase as altitude increases in the stratosphere, particularly in the upper portion – ozone • Temperatures decrease with altitude in the mesosphere • Thermosphere is the first to receive Sun’s rays, so they are very hot

  17. Overview

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