There are many layers of the atmosphere. There is a lot of difference in their properties.
Troposphere - The lowest layer of the atmosphere is called troposphere. 'Tropo' means changing. Hence, Troposphere is that layer in which the temperature changes upward on account of convection current. Height - 16km at the equator and 7 km at the poles. It contains most the atmospheric air (75%).
Stratosphere - Lies above Tropopause (the imaginary line between troposphere and stratosphere). The temperature in the lower part of this sphere does not change with altitude. The temperature is nearly constant upward about 20km and then increases, owing to absorption of ultraviolet radiation by ozone.
Ionosphere - The ionosphere is defined as the layer of the Earth's atmosphere that is ionized by solar and cosmic radiation. It lies 75-1000 km (46-621 miles) above the Earth. Free electrons in this layer help in the conduction of electricity in this sphere.
Mesosphere - The mesosphere starts at 50 km (31 miles) above Earth's surface and goes up to 85 km (53 miles) high. As you get higher up in the mesosphere, the temperature gets colder. The top of the mesosphere is the coldest part of Earth's atmosphere.
Exosphere - The exosphere is the uppermost region of Earth's atmosphere as it gradually fades into the vacuum of space. Air in the exosphere is extremely thin - in many ways, it is almost the same as the airless void of outer space.