The atmosphere consists of 4 layers:
The Troposphere This layer extends approximately 12km from the Earth's surface, with temperature decreasing with altitude by 6.4 degrees Celsius per 1000 metres. This is a particularly unstable layer where there is lots of turbulence, as warm air rises and cooler air descends. Pressure decreases with altitude, and it is these variations within the troposphere that allows the vertical movement and convection of air, leading to cloud formation and the weather we experience on Earth. Cloud formation is also contributed to by the abundance of water vapour that has evaporated from the Earth's surface. There is a boundary between the troposphere and stratosphere, which is called the tropopause, and it marks the limit of weather and climate. Stratosphere The stratosphere extends from approximately 12km to 50km. Unlike the troposphere, temperature in the stratosphere increases with altitude. This is because the ozone (which absorbs UV radiation) is found in the lower stratosphere and this consequentially heats the upper stratosphere. There is little turbulence and few clouds in this layer. The stratopause is known as the boundary between the stratosphere and the mesosphere. Mesosphere The mesosphere extends from 50km to 80-90km, Similarly to the troposphere, temperature decreases with altitude, because this layer is warmed by the stratosphere, however as distance increases from the stratosphere, the temperature decreases. The temperature decrease is far more rapid than in the stratosphere, which is caused by a lack of water vapour, dust and cloud.The mesopause is the boundary between the mesosphere and the thermosphere. Thermosphere This layer extends from 85-90km to 1000km up. Temperature increases rapidly with altitude, as small amounts of oxygen absorb UV radiation, hence warming this layer, with temperatures that can exceed 1000 degrees. Within all four layers of the atmosphere, air pressure decreases with altitude. |