Atmospheric Layers

1. Atmospheric Layers *Celsius 1 = 33.8 Fahrenheit

2. McLayer

3. “McAtmosphere” Illustrate the layers of the atmosphere and label each correctly. Include subtext & miles. Exosphere Thermosphere Mesosphere Stratosphere Troposphere

4. Troposphere The troposphere begins at the surface and extends to between 0 to 8 miles, with some variation due to weather. The troposphere is mostly heated by transfer of energy from the surface, so on average the lowest part of the troposphere is warmest and temperature decreases with altitude. This promotes vertical mixing (hence the origin of its name in the Greek word, tropos, meaning "turn"). The troposphere contains roughly 80% of the mass of the atmosphere and basically all the weather-associated cloud genus types (very tall cumulonimbus thunder clouds can penetrate the stratosphere from below).The tropopause is the boundary between the troposphere and stratosphere.

5. Stratosphere The stratosphere extends from the tropopause at about 7.5 mi to about 32 mi. Temperature increases with height due to increased absorption of ultraviolet radiation by the ozone layer, which restricts turbulence and mixing. While the temperature may be −60 °C (−76 °F; 210 K) at the tropopause, the top of the stratosphere is much warmer, and may be near freezing. Polar stratospheric or nacreous clouds are occasionally seen in this layer of the atmosphere. The stratopause, which is the boundary between the stratosphere and mesosphere, typically is at 31 to 34 mi. The pressure here is 1/1000 sea level.

6. Mesosphere • The mesosphere extends from the stratopause at about 31 mi to 50–53 mi. It is the layer where most meteors burn up upon entering the atmosphere. Temperature decreases with height in the mesosphere. The mesopause, the temperature minimum that marks the top of the mesosphere, is the coldest place on Earth and has an average temperature around −85 °C (−120 °F; 190 K). At this altitude, temperatures may drop to −100 °C (−150 °F). Due to the cold temperature of this layer, water vapor is frozen, occasionally forming polar-mesospheric noctilucent clouds which are the highest water-based aerosols in the atmosphere. A type of lightning referred to as either sprites or ELVES, occasionally form far above tropospheric thunderclouds.

7. Thermosphere • Temperature increases with height in the thermosphere from the mesopause up to the thermopause, then is constant with height. Unlike in the stratosphere, where a temperature inversion is caused by absorption of radiation by ozone, in the thermosphere the inversion is a result of the extremely low density of molecules. The temperature of this layer can rise to 1,500 °C (2,700 °F), though the gas molecules are so far apart that temperature in the usual sense is not well defined. The air is so rarefied that an individual molecule (of oxygen, for example) travels an average of 1 kilometer between collisions with other molecules. The International Space Station orbits in this layer, between 200 and 240 mi. The aurora borealis and aurora australis are occasionally seen in the thermosphere and the lower part of the exosphere. The top of this layer is also the bottom of the exosphere, and is called the exobase. Its height varies with solar activity and ranges from about 220–500 mi.

8. Exosphere The exosphere is the outermost layer of Earth's atmosphere, extending beyond the exobase at an altitude of about 372 mi. It is mainly composed of hydrogen, helium and some heavier molecules such as nitrogen, oxygen and carbon dioxide closer to the exobase. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another, so the atmosphere no longer behaves like a gas. These free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind.

9. Ozone (O3) Layers 90% of the ozone layer is contained within the lower stratosphere, about 9.3–22 mi; the thickness varies seasonally and geographically. In this layer ozone concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere. Air pollution is the introduction into the atmosphere of chemicals, particulate matter, or biological materials that cause harm or discomfort to organisms. Stratospheric ozone depletion is believed to be caused by air pollution (chiefly from chlorofluorocarbons). Build up of CO2

10. Pressure and thickness The average atmospheric pressure at sea level is 1 standard atmosphere (atm)=14.7 psi (pounds per square inch). Atmospheric pressure is the total weight of the air above unit area at the point where the pressure is measured. Thus, air pressure varies with location and weather. If the atmosphere had a uniform density, it would terminate abruptly at an altitude of 5.2 miles. However, the atmosphere is modeled according to gradients of temperature, molecular composition, solar radiation and gravity.

11. Oh yeah, there are more layers in the layers ;-) • ionosphere – between the mesosphere & thermosphere, it is a region that is ionized by solar radiation. This zone creates auroras (Northern Lights). • Magnetosphere-part of the ionosphere, allows radio propagation on Earth. • Homosphere-involves well mixed gasses, due to turbulance, in the first three layers of the Atmosphere. • Heterosphere-in the areas of the exosphere & themosphere, where great distance seperatesparticals, and molecular weight creates more layers.

12. …and another… • planetary boundary layer— part of the troposphere closest to Earth's surface and directly affected by it, through turbulent diffusion. During the day the planetary boundary layer is well-mixed, but at night it becomes stably stratified with weak or intermittent mixing. The depth of the planetary boundary layer ranges from as little as about 100 meters on clear, calm nights to 3000 m or more during the afternoon in dry regions.