KPDS 1999-2 Soru=13

According to the passage, the earth ____ .

Atmosphere is the gaseous envelope of the earth, and
consists of a mixture of gases and water vapour. The
variability of the latter is meteorologically of great
importance. The ozone layer, which absorbs solar ultraviolet
radiation, especially lethal to plant life, lies between
12 and 50 kilometres above the earth. The lower level of
the atmosphere, up to a height of about 12 kilometres, is
known as the troposphere, and it is in this region that
nearly all weather phenomena occur. This is the region of
most interest to the forecaster studying temperature,
humidity, wind-speed and the movement of air masses.