Earth

1
Earths Atmosphere

• The atmosphere is defined as the blanket of gases
  that surround planet Earth.

2
Layers of the Atmosphere(see p.14 of your
reference table)
3
The Troposphere

• The troposphere is the lowest layer of the
  Earth's atmosphere. The air is very well mixed
  and the temperature decreases with altitude.
• Air in the troposphere is heated from the ground
  up. The surface of the Earth absorbs energy and
  heats up faster than the air does.
• Weather occurs in the Earth's troposphere

4
Greenhouse Gases

• Greenhouse gases are found in the troposphere.
• These gases help retain heat, a portion of which
  is then radiated back to warm the surface of
  Earth.

5
What are the greenhouse gases?
6
The Stratosphere

• In the Earth's stratosphere, the temperature
  increases with altitude.
• On Earth, ozone causes the increasing temperature
  in the stratosphere. Ozone is concentrated around
  an altitude of 25 kilometers. The ozone molecules
  absorb dangerous kinds of sunlight, which heats
  the air around them.
• The stratosphere is located above the top of the
  troposphere

7
What is the Ozone Layer?

• The ozone layer forms a thin shield high up in
  the sky. It protects life on Earth from the sun's
  ultraviolet (UV) rays.

8
Whats happening to the Ozone Layer?

• In the 1980s, scientists began finding clues that
  the ozone layer was going away or being depleted.

9
What is the affect of a depleting ozone layer?

• This allows more UV radiation to reach the
  Earth's surface. This can cause people to have a
  greater chance of getting too much UV radiation.
  Too much UV can cause bad health effects like
  skin cancer and eye damage

10
What causes ozone depletion?

• Recently, chlorofluorocarbons (CFCs) were used a
  lot in industry and elsewhere to keep things cold
  and to make foam and soaps.
• Other ozone-eating chemicals are pesticides such
  as methyl bromide, halons used in fire
  extinguishers, and methyl chloroform used in
  businesses.

11
How is the ozone layer broken up?

• Strong winds carry CFCs up into the stratosphere
  where UV radiation breaks them apart, releasing
  chlorine atoms. Each chlorine atom can attack and
  break apart (destroy) as many as 100,000 ozone
  molecules in the stratosphere.
• The chlorine from CFCs reduces the amount of
  ozone in the stratosphere.

12
The Mesosphere

• In the Earth's mesosphere, the air is relatively
  mixed together and the temperature decreases with
  altitude.
• The atmosphere reaches its coldest temperature of
  around -90C in the mesosphere.
• This is also the layer in which a lot of meteors
  burn up while entering the Earth's atmosphere.
• The mesosphere is on top of the stratosphere The
  upper parts of the atmosphere, such as the
  mesosphere, can sometimes be seen by looking at
  the very edge of a planet

13
The Thermosphere

• The thermosphere is the fourth layer of the
  Earth's atmosphere and is located above the
  mesosphere. The air is really thin in the
  thermosphere.
• A small change in energy can cause a large change
  in temperature. That's why the temperature is
  very sensitive to solar activity. When the sun is
  active, the thermosphere can heat up to 1,500 C
  or higher!
• The Earth's thermosphere also includes the region
  of the atmosphere called the ionosphere.

14
The Ionosphere

• The ionosphere is a region of the atmosphere that
  is filled with charged particles. The high
  temperatures in the thermosphere can cause
  molecules to ionize. This is why an ionosphere
  and thermosphere can overlap
• The upper atmosphere is ionized by solar
  radiation. That means the Sun's energy is so
  strong at this level, that it breaks apart
  molecules. So there ends up being electrons
  floating around and molecules which have lost or
  gained electrons. When the Sun is active, more
  and more ionization happens!

15
What are Auroras?

• http//www.exploratorium.edu/learning_studio/auror
  as/selfguide1.html

16
What are Auroras or Northern Lights?

• The bright dancing lights of the aurora are
  actually collisions between electrically charged
  particles from the sun that enter the earth's
  atmosphere.
• The lights are seen above the magnetic poles of
  the northern and southern hemispheres.
• They are known as 'Aurora borealis' in the north
  and 'Aurora australis' in the south

17
Aurora

• A sinuous glowing band of aurora (the Aurora
  Australis or Southern Lights) loops around the
  southern polarregion in the distance as viewed by
  astronauts onboard the space shuttle on STS-039.
  Aurora are produced when energetic particles
  entering the Earth's atmosphere from space
  interact with atoms and molecules in the
  atmosphere and release energy, emitted as light

18
The Exosphere

• Very high up, the Earth's atmosphere becomes very
  thin.
• The region where atoms and molecules escape into
  space is referred to as the exosphere.
• The exosphere is on top of the thermosphere.