Transcript Atmosphere - sciencewithpace

Chapter 19
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Do Now:
Atmosphere - a mixture of gases that surrounds a
planet, such as Earth
 abundant elements = nitrogen, oxygen, &
argon
 abundant compounds = carbon dioxide (CO2),
& water vapor (H2O)
 carries various kinds of tiny solid particles, like
dust & pollen
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Makes up about 78% of Earth’s atmosphere
Maintained through the Nitrogen Cycle
1. removed from air by nitrogen-fixing bacteria
2. bacteria change nitrogen into compounds plants use
3. decay releases nitrogen back into the atmosphere
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Makes up about
21% of
atmosphere
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Animals, bacteria,
& plants remove
oxygen from the
air
Plants make
oxygen during
photosynthesis
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Water evaporates from oceans, lakes, streams,
& soil
It enters air as the invisible gas, water vapor
It is removed by condensation & precipitation
Amount of water vapor in the atmosphere
depends on:
 time of day
 Location
 season
Ozone (O3)- gas molecule made up
of three oxygen atoms
 Forms the ozone layer
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absorbs harmful ultraviolet (UV)
radiation from sun
Without the ozone layer, living
organisms would be severely
damaged by the sun’s ultraviolet
rays
Human activities damage the
ozone layer 
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The atmosphere contains various tiny solid & liquid
particles, called particulates.
Particulates can be:
 volcanic dust, ash, microscopic organisms
 pollen & particles from meteors
Heavy particles don’t remain in the atmosphere for
long, but tiny particles can remain suspended in the
atmosphere for months or years.
Gravity holds the gases of the atmosphere near
Earth’s surface.
Atmospheric pressure - force per unit area that is
exerted on a surface by the weight of the
atmosphere
 Atmospheric pressure is exerted equally in all
directions—up, down, & sideways.
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Atmospheric pressure changes with:
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Temperature
Altitude
Water Vapor
As temperature
atmospheric pressure
As altitude
atmospheric pressure
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Meteorologists use three units for atmospheric
pressure:
atmospheres (atm)
 millimeters or inches of mercury
 millibars (mb)
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The average atmospheric pressure at sea level
is 1 atm.
Meteorologists measure atmospheric pressure
by using an instrument called a barometer.
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One type of barometer
is the mercurial
barometer.
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Pressure presses on the
liquid mercury
Height of the mercury
changes
The greater the
atmospheric pressure is,
the higher the mercury
rises
1. The Troposphere
lowest layer
part where weather conditions exist
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2. The Stratosphere
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contains the ozone layer
3. The Mesosphere
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coldest layer of the atmosphere
4. The Thermosphere
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uppermost layer of the atmosphere
includes the ionosphere & the phenomena known as
auroras.
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Any substance in the atmosphere that is
harmful to people, animals, plants, or property
is called an air pollutant.
The main source of air pollution is the burning
of fossil fuels, such as coal & petroleum.
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Do Now:
Radiation - includes all forms of energy that
travel through space as waves.
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travels at a very high speed — 300,000 km/s.
types of radiation differ in the length of their waves
Electromagnetic spectrum - all of the frequencies
or wavelengths of electromagnetic radiation
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Clouds, dust, & water disrupt the paths of radiation
from the sun & causes scattering.
Scattering - occurs when particles & gas molecules in the
atmosphere reflect & bend solar rays.
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causes rays to travel out in all directions without
changing their wavelength
Albedo - fraction of solar
radiation that is reflected
off the surface of an
object
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Depends on color,
texture, composition,
volume, mass,
transparency, state of
matter, & specific heat of
the material.
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Solar radiation that is not reflected is absorbed
by rocks, soil, & water.
It heats the surface.
Sometimes, warm air bends light rays to
produce an effect called a mirage.
Greenhouse effect - warming of the surface &
lower atmosphere of Earth that occurs when
carbon dioxide, & water vapor absorb &
reradiate radiation
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The amount of solar E that enters Earth usually
equals the amount that escapes into space.
However, human activities, in addition to
natural causes, are changing the balance
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causing temperature to increase
Increases in carbon dioxide may intensify the
greenhouse effect & may cause Earth to
become warmer.
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Radiation from the sun does not heat Earth
equally at all places at all times.
Temperature of the atmosphere depends on:
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Latitude
Surface features
Time of year & day
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Latitude is the primary factor that affects the
amount of solar energy on Earth.
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Because Earth is a sphere, the sun’s rays do not strike
all areas at the same angle.
Temperature varies seasonally because of the
tilt of Earth’s axis.
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The molecules in a substance move faster as
they become heated.
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collide & transfer energy, which warms the new
substance.
Conduction - transfer of energy as heat from one
substance to another by direct contact.
Convection – process by which air or other matter
rises or sinks b/c of differences in temperature.
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Heats Earth’s atmosphere
Causes winds
Conduction
Convection
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Do Now:
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The circulation of the atmosphere & oceans is
affected by Earth’s rotation.
Coriolis effect - curving of the path of a
moving object from an otherwise straight path
due to Earth’s rotation
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Deflects a moving object along a path
Depends on speed, latitude, & direction of the object
Northern hemisphere = to right
Southern hemisphere = left
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Air that flows from the poles to the equator
does NOT flow in a straight line.
Each hemisphere contains three looping
patterns of flow called convection cells.
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Each correlates to an area of Earth’s surface, called a
wind belt, that is characterized by winds that flow in
one direction.
These winds are called prevailing winds.
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Trade winds, westerlies, polar easterlies
Trade wind - prevailing winds that blow from
east to west from 30º latitude to the equator in
both hemispheres
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named according to the direction from which they
flow
Northern Hemisphere trade winds = northeast
trade winds
Southern Hemisphere = southeast trade winds
Westerlies - prevailing winds that blow from
west to east between 30º and 60º latitude in
both hemispheres
Polar easterlies - prevailing winds that blow from
east to west between 60 and 90 latitude in both
hemispheres
 Where the polar easterlies meet warm air from
the westerlies, a stormy region known as a
front forms.
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Local winds are not part of the global wind
belts.
Breezes - blow at speeds of less than 50
 Sea Breeze - cool wind moving from water to land
 Land breeze - flows from cool land towards the
water
 Valley breeze - warm air from the valleys moves
upslope
 Mountain breeze - cool air descends from the
mountain peaks.
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