Download The Atmosphere

The Atmosphere
The elements according to the Greeks:
They believed these could not be broken down into parts.
What is the
Atmosphere?
• The atmosphere is a layer
of gases that surrounds
Earth. It extends into outer
space.
• Imagine Earth as an apple.
If you breathe on the apple,
and a thin film of water
droplets forms on the
surface, the atmosphere is
like that thin layer of water
on the apple.
What do we know
today about the air
around us?
What are the gases
that make up the
atmosphere?
• It is made of many gases.
• 99% of air is Nitrogen (78%)
and Oxygen (21%). The
other 1% is a mixture of
water vapor, argon, carbon
dioxide, and other gases.
Why is the atmosphere
• Without the atmosphere,
important to us?
there would be no life on our
planet.
Gases in the atmosphere
How do the gases of the
atmosphere change?
• The amounts of
Nitrogen and Oxygen
in the atmosphere
don’t change.
• The amount of the
other gases changes,
especially water
vapor in the air which
always changes.
How does water
vapor change in the
atmosphere?
• The amount of water
vapor in the air is
always changing. It is
different over different
parts of the world. It
may change over an
area within a period of
a day or even a few
hours.
• Water vapor may
make up as much as
four percent (4%) of
the atmosphere.
What causes the
changes in water
vapor in the
atmosphere?
• The % of water vapor
changes with the seasons.
• Warmer air can hold more
moisture than cooler air.
• So there is more water
vapor in the air in spring and
summer.
• The air in fall and winter is
cooler and dryer. It doesn't
contain as much water
vapor.
What effect does the
• Our weather changes because
of differences in the amounts of
change in water vapor
water vapor in the air.
have on our weather?
• Clouds, rain, and snow come
from water vapor.
• Water is the only substance in
our atmosphere that comes in
three states (also known as
forms or phases). It can be
solid, liquid, or gas.
• When it changes from one state
to the other, heat is soaked up
or given off. This makes the
gases in the atmosphere move
and creates weather.
What other things
are found in the
atmosphere?
• There are solid particles in
the atmosphere.
• Dust and salt are left behind
during evaporation. Volcanic
eruptions and wind also send
solid particle into the
atmosphere.
• These help clouds to form.
• This also affects our weather.
• Ice is another solid found in
the air. This usually comes in
the form of hail or sleet.
Layers of the atmosphere
• The atmosphere is made up of several layers.
The Troposphere
• The layer closest to the earth is the troposphere.
• This is where most of the water vapor is. Most weather
takes place in this layer.
• The air temperature, pressure and density decrease
as you go from the bottom to the top of the troposphere.
The Stratosphere
• The next layer is called the
stratosphere.
• Ozone is found here. This is a
layer of special oxygen
molecules high above the
earth. It absorbs harmful rays of
the sun. If there were no ozone,
the sun would badly damage our
skin.
• The stratosphere is warm
because it blocks much of the
radiation from the sun. The top
of the stratosphere is about 50
km above the earth's surface.
The Mesosphere and the
Thermosphere
• Above the stratosphere is the mesosphere.
• This layer is the coldest layer because there is
no ozone here.
• Beyond the mesosphere is the thermosphere.
The temperature in this layer is more than 1000
degrees Celsius. This layer is very thin. The
molecules are spread out. So it wouldn't feel
that hot to you if you were to go through it.
The Ionosphere and the Exosphere
• Next comes the ionosphere.
• This is actually part of the thermosphere. It is
made of layers of very light gases.
• The last layer is the exosphere. Hydrogen and
helium are found here. Beyond this layer is outer
space.
• But you won't "bump into" outer space. There is
no ceiling at the end of the atmosphere. The
molecules are just spaced farther apart until they
don't exist anymore.
Animals need air to breathe.
Plant life needs gases in the
air for photosynthesis. Life
on earth could not exist without
the atmosphere.