The document describes the different layers of Earth's atmosphere: 1) The troposphere is where weather occurs and air pressure decreases with altitude. 2) Above the troposphere is the stratosphere, which contains the ozone layer that absorbs ultraviolet radiation. Concerns exist that man-made compounds may deplete the ozone layer. 3) The mesosphere separates the stratosphere from the thermosphere, and temperature decreases with increasing altitude in this layer.

1. ATMOSPHERE Layers of
Atmosphe
re

2. ATMOSPHERE
 An atmosphere (New Latin atmosphaera, created in the 17th
century from Greek ἀτμός [atmos] "vapor" [1] and σφαῖρα
[sphaira] "sphere" [2] ) is a layer ofgases that may surround a
material body of suf ficient mass, [3] and that is held in place
by the gravity of the body. An atmosphere may be retained for
a longer duration, if the gravity is high and the atmosphere's
temperature is low. Some planets consist mainly of various
gases, but only their outer layer is their atmosphere.

4. LAYERS OF ATMOSPHERE
 The Troposphere
 The troposphere is where all weather takes place; it is the
region of rising and falling packets of air. The air pressure at
the top of the troposphere is only 10% of that at sea level (0.1
atmospheres). There is a thin buffer zone between the
troposphere and the next layer called the tropopause.

5. STRATOSPHERE
 The Stratosphere and Ozone Layer
 Above the troposphere is the stratosphere, where air flow is
mostly horizontal. The thin ozone layer in the upper
stratosphere has a high concentration of ozone, a particularly
reactive form of oxygen. This layer is primarily responsible for
absorbing the ultraviolet radiation from the Sun. The
formation of this layer is a delicate matter, since only when
oxygen is produced in the atmosphere can an ozone layer
form and prevent an intense flux of ultraviolet radiation from
reaching the surface, where it is quite hazardous to the
evolution of life. There is considerable recent concern that
manmade flourocarbon compounds may be depleting the
ozone layer, with dire future consequences for life on the
Earth

6. MESOSPHERE
 The mesosphere (/ˈmɛs oʊs fɪ ər/; from Greek mesos = middle
and sphaira = ball) is the layer of the Earth's atmosphere that is directly
above the stratosphere and directl y below the thermosphere . In the
mesosphere temperature decreases with increasing height. The upper
boundary of the mesosphere is the mesopause , which can be the coldest
naturall y occurring place on Earth with temperatures below 130 K. 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, except at middle and high
latitudes in summer where it descends to heights of about 85 km.
 The stratos phere, mesosphere and lowest part of the thermosphere are
collectively referred to as the "middle atmosphere", which spans heights
from approxi matel y 10 to 100 km. The mesopause , at an altitude of 80 –
90 km (50–56 mi), separates the mesosphere from thether mos phere —the
second-outermos t layer of the Earth's atmosphere. This is also around
the same altitude as the turbopause , below which different chemical
species are well mixed due to turbulent eddies. Above this level the
atmosphere becomes non -uni form; the scale heights of different
chemical species differ by their molecular masses .

7. IONOSPHERE
 The ionosphere is a part of the upper atmosphere, from
about 85 km (53 mi) to 600 km (370 mi) altitude, comprising
portions of the mesosphere, thermosphere and exosphere,
distinguished because it is ionized by solar radiation. It
plays an important part in atmospheric electricity and forms
the inner edge of the magnetosphere. It has practical
importance because, among other functions, it
influences radio propagation to distant places on
the Earth. [1]

8. LAYERS OF ATMOSPHERE