Air Test - 6

According to NASA, the gases in Earth's atmosphere include: Nitrogen — 78 percent. Oxygen — 21 percent. Argon — 0.93 percent.

Trade winds permanently blows from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere. They are the surface winds found in the tropics within the lower portion of the Earth's atmosphere. Trade winds helped sailors to travel across the world since centuries.

The atmosphere of Earth is composed of nitrogen (about 78%), oxygen (about 21%), argon (about 0.9%), carbon dioxide (0.04%) and other gases in trace amounts.

Earth's atmosphere consists a series of layers having their own specific traits. There layers are arranged in ascending order from the Earth's surface. 

The atmospheric layer that supports life is called troposphere. It is the lowest layer of earth’s atmosphere. The troposphere starts at Earth's surface and goes up to a height of 7 Km to 16 km. Almost all weather phenomenon occur in this layer.  

Troposphere is the lower most layer of the earth. It extends from earth’s surface and goes up to a height of 12 km. But its height varies from place to place and from season to season. Almost all weather phenomenon occur in this layer. Air is warmest at the bottom of the troposphere near ground level. But there is a decrease of temperature with increasing height.

The troposphere starts at the Earth's surface and extends 8 to 14.5 km high (5 to 9 miles). This part of the atmosphere is the most dense. Almost all weather is in this region.

The layer present between stratosphere and thermosphere is mesosphere. Height of mesosphere layer is 80-85 kms. It is the layer present between stratosphere and thermosphere. In the mesosphere, temperature decreases as the altitude increases. The upper boundary of the mesosphere is the mesopause, which is the coldest naturally occurring place on Earth.

The rain shadow effect refers to the formation of a dry area due to the effect of a topographic barrier, especially a mountain range. A rain shadow is formed when wind carries moist air towards the mountain. The height of the mountain forces the moist air upwards where it condenses and precipitates. This rainfall is orographic rainfall. The leeward side is the rain shadow area. 

The layer of earth above mesosphere is thermosphere. It consists of ions due to ultra violet radiations causing photo ionization and hence forms ionosphere.  The temperature in this zone increases with increase in altitude.