Transcript Chapter 15 The Atmosphere

Chapter 15
The Atmosphere
The Air Around You
Weather and the Atmosphere
• Weather is the condition of Earth’s
atmosphere at a particular time
and place.
• Atmosphere is the layer of gases
that surrounds the planet.
• Earth’s atmosphere makes
conditions on Earth suitable for
living things.
• The atmosphere is always
changing
Earth’s Atmosphere:
1. Traps energy from the sun (liquid
water).
2. Protects from dangerous
radiation.
3. Prevents Earth’s surface from
being struck by meteroids.
Composition
• The atmosphere is made up of a
mixture of molecules of different
kinds of gases.
Composition
Composition
• Earth’s atmosphere (greatest to least)
1. Nitrogen = 78%
2. Oxygen = 21%
3. Carbon dioxide
4. Water vapor
5. Trace gases
Nitrogen
• Is essential to living things, it helps
grow and repair body cells.
• Most organisms cannot use
nitrogen directly. However,
bacteria converts nitrogen to
nitrates and is easily used.
Oxygen
• Oxygen can be used directly.
• All fuels use oxygen as they burn.
Ozone
• Ozone is a form of oxygen that has
three oxygen atoms in each molecule
instead of two.
Carbon Dioxide
• When most fuels are burned they
release carbon dioxide.
• Rising carbon dioxide levels may
be raising Earth’s temperature.
• O and N together make up 99 % of
dry air.
Water Vapor
• Water vapor is water in a gaseous
state.
• The amount of water vapor in the
air varies from place to place and
from time to time.
• Plays a major role in Earth’s
weather.
Particles
• Air contains tiny solid and liquid
particles of dust, smoke, salt, and
other chemicals.
Air Quality
Air Pollution
• Most air pollution is the result of
burning fossil fuels such as coal, oil,
gasoline, and diesel fuel.
• Air pollution includes particles from:
– Human activities
• (farming, construction, burning etc.)
– Natural sources
• (wave action, mold, forest fires, volcanoes,
etc).
Smog
• Smog is the result of smoke mixing
with water droplets.
• Photochemical smog is caused by the
action of sunlight on chemicals. It
often looks like a brown haze.
Smog
• High temperatures + oxygen=nitrogen
oxides.
• Nitrogen oxides + hydrocarbons +
sunlight=ozone and other chemicals
(photochemical smog)
Smog
• Smog can cause respiratory illness
and distress.
• Scientists created a system that
publicly indicates the quality of air
and presence of air pollution.
Temperature Inversion
• Normally, air close to the ground is
heated and carried up into the
atmosphere (carrying the pollution with
it).
• However, during a temperature
inversion a layer of warm air prevents
the polluted air from being carried
away.
Acid Rain
• Acid rain forms when nitrogen
oxides and sulfur oxides combine
with water in the air to form nitric
acid and sulfuric acid.
Montreal Protocol
• January 1, 1989 – an international treaty
designed to protect the ozone layer by
phasing out the production of CFC’s, which
are understood to deplete the ozone layer.
• Kyoto Protocol – prevention
Of climate change.
• These actions are aimed at preventing
Global warming
Air Pressure
Properties of Air
1. Mass
2. Density
3. Pressure
Air Pressure
• Air pressure is measured with a
barometer.
• There are two kinds of barometers:
–Mercury barometer
–Aneroid barometer
Mercury Barometer
• The first kind to be created.
• Glass tube filled with mercury.
• As the air pushes down, the
mercury rises in the tube.
• Pressure subsides, the mercury
falls in the tube.
Aneroid Barometer
• Is an airtight metal chamber.
• Uses a series of springs and
levers.
• As the air is pushing down, a metal
chamber bulges moving a hand on
a dial.
Air Pressure
• Air pressure is reported and
recorded in:
1. Inches of mercury
2. Millibars
30”=1,016 millibars
Air Pressure & Altitude
• Altitude (elevation) is the distance
above sea level.
• Air pressure decreases as altitude
increases.
• As air pressure decreases, so does
density.
Air Pressure & Altitude
• Altitude↑=Air pressure↓=Density↓
• Altitude ↓=Air pressure ↑=Density ↑
Layers of the Atmosphere
Layers of the Atmosphere
• The layers of the atmosphere are
classified according to:
–Changes in temperature
Layers of the Atmosphere
1.
2.
3.
4.
Troposphere
Stratosphere
Mesosphere
Thermosphere
1. Ionosphere
2. Exosphere
Troposphere
• Tropo- means “turning” or “changing”.
• Conditions in the troposphere change
more than in any other layer.
• Where we live
• Weather occurs here
Troposphere
• Weather balloons (expand the higher
they go – more room to expand).
• Depth varies:
– 16 km thick above the equator
– 9 km thick above the north and south
poles
• As altitude increases, temperature
decreases.
Stratosphere
• Extends from the top of the
troposphere to about 50km.
• The upper stratosphere is warmer
than the lower stratosphere.
• Ozone layer
• Weather balloons burst
Mesosphere
• Meso- means “middle” layer
• Most meteors burn up producing
meteor trails.
• 50 to 80 km
• Temperatures -90°C
Thermosphere
• Thermo- means “heat”
• The outermost layer of the atmosphere.
• No definite outer limit.
• Temperatures up to 1,800°C
Thermosphere
• Is divided into 2 layers:
–Ionosphere (lower)
–Exosphere (outer)
Ionosphere
• Begins 80 km above the surface
and extends to 550 km.
• Energy from the sun causes gas
molecules to become electrically
charged ions.
Ionosphere
• Aurora borealis (Northern Lights)
brilliant light display caused when
charged particles enter.
• Radio waves bounce back to
Earth’s surface.
Exosphere
• Exo- means “outer”.
• Begins at 550 km above the Earth
and extends outward for
thousands of kilometers.
• Satellites orbit here.
Energy in the Atmosphere
Energy in the Atmosphere
• Nearly all the energy in Earth’s
atmosphere comes from the sun.
• The energy travels to Earth as
electromagnetic waves.
• Electromagnetic waves can
transmit energy through the
vacuum of space.
Energy in the Atmosphere
• Radiation is the direct transfer of
energy by electromagnetic waves.
• Most of the energy from the sun
reaches Earth in the form of:
–Visible light
–Infrared radiation
–Ultraviolet radiation
Energy in the Atmosphere
• Visible light is a mixture of all the
colors that you see in a rainbow.
– Red
– Orange
– Yellow
– Green
– Blue
– Indigo
– Violet
• ROY G BIV
(Longer)
(Shorter)
Energy in the Atmosphere
• The different colors are a result in
difference in wavelength
• Infrared radiation has longer
wavelengths than visible light.
• Ultraviolet radiation has shorter
wavelengths than visible light
Energy in the Atmosphere
• Some energy is absorbed:
– Water vapor and CO2 absorb IR
– The ozone layer absorbs UV
– Clouds, dust, & other gases absorb
energy from the sun.
Energy in the Atmosphere
• Some energy is reflected:
– Clouds reflect
– Dust particles and gases (in all
directions=scattering)
• Gas molecules scatter short
wavelengths of visible light
(blue/violet) more than longer
wavelengths (red/orange)
Energy in the Atmosphere
• Scattered light is more blue
(daytime sky is blue).
• During the sunrise and sunset the
majority of the blue light is
scattered due to the height of the
sun causing the sky to appear red.
Energy at Earth’s Surface
• When Earth’s surface is heated, it
radiates some of the energy back
into the atmosphere as infrared
radiation.
• Most of the IR cannot travel back
into space; most absorbed by
water vapor, CO2, etc.
Energy at Earth’s Surface
• The process by which these gases
hold heat in the air is called the
greenhouse effect.