The Atmosphere
Did you know we are on our 3
atmosphere on Earth?
• Earth’s original atmosphere was probably just
hydrogen and helium, because these were the
main gases in the dusty, gassy disk around the
Sun from which the planets formed.
•
And in second place we have…
• Earth’s “second atmosphere” came from Earth
itself. There were lots of volcanoes, many
more than today, because Earth’s crust was
still forming.
Currently…..
• Current Earth: Plants and animals thrive in
balance. Plants take in carbon dioxide (CO2)
and give off oxygen (O2). Animals take in
oxygen (O2) and give off CO2. Burning stuff
also gives off CO2.
The atmosphere upon which life
depends was created by life itself.
• Now we have Earth’s “third atmosphere,” the
one we all know and love—an atmosphere
containing enough oxygen for animals,
including ourselves, to evolve.
• So plants and some bacteria use carbon
dioxide and give off oxygen, and animals use
oxygen and give off carbon-dioxide—how
convenient!
• The atmosphere has 4 layers:
• the troposphere that we live in near the
surface of the earth;
• the stratosphere that houses the ozone layer;
• the mesosphere, a colder and lower density
layer with about 0.1% of the atmosphere;
• and the thermosphere, the top layer, where
the air is hot but very thin.
Why do I care?
The structure of the atmosphere dictates the
way the atmosphere behaves and controls how
weather develops near the surface of the earth.
Temperature decreases with height in
the troposphere.
• This is true for a couple different reasons.
First, even though the sun's energy comes
down from the sky, it is mostly absorbed by
the ground.
• The ground is constantly releasing this energy,
as heat in infrared light, so the troposphere is
actually heated from the ground up, causing it
to be warmer near the surface and cooler
higher up.
• Another reason is the decreasing air pressure
with height. If the warm air at the surface gets
blown upward into the cooler air above it, the
surface air will continue to rise
• The constantly decreasing air pressure in
conjunction with the ground-up heating
keeps the temperature in the troposphere
decreasing with height.
• In the real atmosphere, the actual vertical
temperature structure depends on air masses
with specific properties of temperature and
humidity being blown into the area as well as
effects of daytime heating.
• If you have a layer of air with warm temperatures
above the surface, we call that an "inversion".
That layer can act as a cap which prevents clouds
and sometimes severe weather from forming.
Weather…………….
As the popular saying goes, "Climate is what you
expect, and weather is what you get!".
• Weather is considered to be the atmospheric
conditions that are happening now or within a
few days.
• On the other hand, Climate represents the
long term atmospheric patterns within which
weather occurs.
Causes of Climate Change
• The climate of the earth fluctuates, and there are
many things that affect it. Volcanoes, changes in
the orbit and the sun, greenhouse gases and the
properties of the earth itself have influence over
the climate.
• Why do I care?
• The climate of the earth is constantly changing
and one should understand all the reasons why
and how these changes impact the surrounding
environment.
• The earth has only had its current atmosphere
for about 400 million years. In that time,
Earth has had climates ranging from being
almost completely covered in ice to times
when even the poles were subtropical
• The current global average temperature is
59°F (15°C, 288K), but it is not staying
constant.
• A few main factors and feedbacks are the
driving forces for climate change.
• These include volcanoes, the Earth’s orbit
around the sun, solar output, green house gas
concentrations, and feedbacks
Why are there different climate
regions?
• Because of the tilt of the Earth and it’s orbit,
different regions have different climates.
• Therefore the number of hours of daylight and
amount of solar radiation varies in differing
locations on the planet.
How does temperature affect
precipitation?
• What do you think the temperature will do to
the type of precipitation that is present?
• If it is very cold, what are the possibilities?
• Temperature will determine if it will be rain,
snow, sleet, fog, or hail
Some questions to think about
• Can you compare and contrast weather and
climate?
• How many layers does the atmosphere have?
• How many atmospheres has the Earth had so far?
• What kind of climate do we live in?
• How did the Earth acquire it’s atmosphere?
• What are climate regions?
• Why do different regions have different climates?