The atmosphere is made up of five layers namely Troposphere, Stratosphere, Mesosphere, Troposphere and an the outer space called exosphere. The boundaries of these layers is the “pause”.
Troposphere
This is the atmosphere we live in and all natural weather phenomenons occur. It stretches to about 11 km from the ground but this varies with latitude or seasons e.g its thick around the equator than poles. The troposphere makes 75% of earth’s atmosphere/Temperature in the troposphere decreases as we ascend high from the earth’s surface. The default drop in temperature is 6.5o100mand is referred to as ENVIROMENTAL LAPSE RATE.
Exhibits the highest temperatures as radiation from the sun warms the Earth’s surface which then warms the air directly above it by the process of convection, conduction and radiation. The air eventually condenses to form clouds, torrential rainfalls, tropical storms and other products of condensation.Unstable weather conditions are most common due to more water vapour supplied from water bodies.
Wind speeds are high at higher elevations due to air moving freely than at earth’s surface were friction is more pronounced.
The upper boundary of the troposphere is the tropopause.
Stratosphere
Stretches to about 50 km. The temperature first rises constantly and start increasing(see diagram).
Temperature rises as we go high due to the concentration of “Ozone”. Ozone traps the incoming ultra-violet radiation from the sun. Without ozone all forms of life on earth will not survive. The upper boundary is the “stratopause”.
Mesosphere
The bulk of the atmosphere mass is in the troposphere and stratosphere which constitutes 99.9% the remaining 0.1 % lies in the mesosphere and themosphere. Stretches from about 50km to 80km (see diagram)
Temperatures rapidly decrease with height and thus is much more cooler with temperatures below -140oC.
Wind speeds are again high.
Themosphere
Temperatures are very high, as ultra-violet radiation heats this layer first. Beyond this layer is the outer space or exosphere thus no themopause.
