2.3. Mesosphere

The mesosphere lies above the stratopause, and extends up to a height of 80 km from 50km. In this layer, once again, temperature starts decreasing with the increase in altitude and reaches up to minus 100° C at the height of 80 km. It is the coldest layer in the atmosphere. The exact upper and lower boundaries of the mesosphere vary with latitude and with season, but the lower boundary of the mesosphere is usually located at heights of about 50 km above the Earth's surface and the mesopause is usually at heights near 100 km. In summers, the height of mesosphere descends down to 85km at middle and high latitudes. The upper limit of mesosphere is known as the mesopause.