The Layered Atmosphere:

Solar Radiation Radio waves, television waves, and microwaves, light, X-rays and gamma rays are all types of electromagnetic waves. They only differ from each other in wavelength. Wavelength is the distance between one wave crest to the next. The Sun emits throughout the electromagnetic spectrum, and the different parts of the spectrum control the structure of our atmosphere.

Layered Atmosphere

"region of mixing" and is so named because of vigorous convective air currents within the layer. Troposphere Visible light is absorbed by the ground Energy reradiated in the form of Infrared and this energy heats the troposphere The troposphere contains 99 % of the water vapor in the atmosphere.

Top of the Troposphere All weather phenomena occur within the troposphere Top of the tropopshere is called the Tropopause 8 km in high latitudes, to 18 km above the equator. Its height also varies with the seasons; highest in the summer and lowest in the winter.

Stratosphere Layered region: between 10 and 50 km above the planet's surface. Region is heated by the Absorption by Ozone of Ultraviolet Radiation Therefore temperature increases with ozone concentration. Little Convection Strong Horizontal winds

Approximately 90 % of the ozone in the atmosphere resides in the stratosphere. UV that is absorbed would otherwise be harmful to life because they can be absorbed by the nucleic acid in cells. Increased penetration of ultraviolet radiation to the planet's surface would damage plant life and have harmful environmental consequences. Appreciably large amounts of solar ultraviolet radiation would result in a host of biological effects, such as a dramatic increase in cancers.

Mesosphere Decreasing temperature decreases 190-180 K (-83 to -93 0C) Layer between 50 and 80 km. Radiosonde - an instrument package that moves through the atmosphere, usually attached to a balloon, and transmits data over a radio frequency

Mesosphere concentrations of ozone and water vapor are negligible. the atmosphere becomes enriched with lighter gases. At very high altitudes, the gases begin to form into layers according to molecular mass (weight), because the force of gravity is greater on the heavier molecules. foreign bodies (such as meteors and spacecraft) entering the atmosphere start to warm up.

Red Sprites Sprites are massive but weak luminous flashes extend from the cloud tops to altitudes up to about 95 km occur in decaying portions of thunderstorms and are correlated with large positive cloud-to- ground lightning strokes. Short lived – 1 ms, total power 10-100 MJ and 5-50 GW

Thermosphere The temperature increases with altitude up to 1000-1500 K. This increase in temperature is due to the absorption of EUV/Xrays by the limited amount of remaining molecular oxygen. At an altitude of 100-200 km, the major atmospheric components are still nitrogen and oxygen. It is within the thermosphere that the aurora phenomena may be observed.

Most distant atmospheric region: extending several thousand km into space. The region represents a transition between Earth’s atmosphere and interplanetary space. Gas in the region have attained sufficiently high energy that they are in orbit around the Earth Neutral density in the region falls below the density of ionized particles, or plasma. Exosphere

Charged and Neutral Structure ionosphere Not shown: Exosphere (neutral) and Magnetosphere (charged)

Atmospheric Layers Each planetary body has a distinct layering scheme. Not all planets have the same layers. Some sets of governing parameters produce similar conditions in all atmospheres where they occur. There are 7 such regions of which the Earth has all 7: The Troposphere: 0-10km (Turbulent weather, decreasing Temp) The Stratosphere: 10-50 km (stable with increasing Temp) The Mesosphere: 50-80 km (highly chaotic, decreasing Temp) The Thermosphere: 100-600 km (Very hot and variable) The Exosphere: 300+ km (Unbound gasses escape Earth) The Ionosphere: 100-600 km (Distinct layers in the thermosphere) The Magnetosphere: (Space region inside Earth’s magnetic field)

Aurora