Download Chapter 14: The Atmosphere

Chapter 11: The Atmosphere
I. Earth’s Atmosphere
A. Atmospheric Gases
1. Composition
a) 78% Nitrogen
b) 21% Oxygen
c) Other=methane, krypton, xenon, hydrogen
2. Ozone in the atmosphere
a) upper atmosphere-protects us from harmful radiation
b) lower atmosphere-harmful pollutant
B. Atmospheric Solids and Liquids
1. Dust
a) wind picks it up and puts it in the atmosphere
2. Ice
a) hailstones
b) snowflakes
3. Salt
a) picked up in the atmosphere from ocean spray
4. Atmospheric Liquids
a) water is the most common liquid, found in the droplets of clouds
b) water is the only substance found as a solid, liquid, and gas
C. Five Main Atmospheric Layers
1. Troposphere
a) the layer we live in
b) contains 75% of atmospheric gases, dust, ice, and liquid water
c) weather, clouds, and smog occur in this layer
2. Stratosphere
a) above the troposphere
b) contains the ozone layer
c) contains the jet stream
3. Mesosphere
a) above the stratosphere
b) middle layer of the atmosphere
c) extreme cold temperatures
4. Thermosphere
a) above the mesosphere
b) very high temperatures
c) objects from space burn up in this layer
d) The Auroras occur here (northern lights)
e) contains the ionosphere: layer of electrically charged particles
that bounces radio waves back to Earth
5. Exosphere
a) above the thermosphere
b) the outermost layer of the atmosphere before space
c) very few air molecules present
D. Atmospheric Pressure
1
1. Pressure is caused by the weight of the gases in the top of the
atmosphere
a) molecules above push down on molecules below
b) density increases as you travel toward the Earth
2. Air pressure is greatest at sea level
a) decreases as altitude increases
E. Atmospheric Temperatures
1. Warm air
a) less dense
b) forms an area of low pressure
2. Cold air
a) more dense
b) forms an area of high pressure
3. The areas of low and high pressure are seen on weather maps
4. Earth’s atmosphere is heated when the molecules absorb energy from
the Sun
5. Certain gases cause different parts of the atmosphere to be warmer than
others
a) Troposphere: colder as altitude increases
b) Stratosphere: warmer as altitude increases, caused by the ozone
layer
c) Figure 14-6 pg. 398
II. The Ozone Layer
A. What is the Ozone Layer?
1. Characteristics
a) 20 km up in atmosphere
b) made of three oxygen molecules (O3)
c) shields us from harmful radiation
2. Ultraviolet Radiation (UV)
a) too much exposure can be dangerous
b) can damage plants and animals
c) is the main cause of skin cancer
d) 800,000 people each year develop skin cancer
e) 9,000 people die each year of skin cancer
3. Holes have developed in the ozone layer
a) largest hole is located over Antarctica
b) smaller hole is located over the North Pole
c) major cause of the melting of polar ice caps
4. The ozone layer is thinning all the way over the Earth
B. Depleting Ozone Layer
1. Pollutants are destroying the ozone layer
2. Chlorofluorocarbons (CFCs)
a) chemicals found in household objects
b) refrigerators, aerosols sprays, Styrofoam
c) contain chlorine atoms which destroy ozone
d) turns ozone (O3) into oxygen (O2), the oxygen does not destroy
radiation
e) One chlorine atom destroys 100,000 Ozone molecules
2
III. Energy from the Sun
A. The Sun
1. Source of ALL energy in the atmosphere
2. Energy loss
a) reflected back into space
b) absorbed by the atmosphere
c) absorbed by land and water
B. Radiation
1. Transfer of energy by electromagnetic waves
a) radiation from the sun travels through space and the atmosphere
b) Sun’s radiation is in the form of light and heat
2. Heat
a) energy flows from an object of higher temperature to an object
of lower temperature
b) “Flow goes from high to low”
3. Most of the Sun’s radiation passes through the atmosphere
a) this radiation has shorter wavelengths
b) the radiation has a higher amount of energy
4. Radiation from Earth
a) is absorbed and heats up the atmosphere
b) longer wavelengths, lower energy
c) radiation does not escape the atmosphere
5. Some of the Sun’s radiation is reflected back and never absorbed by the
Earth
a) Clouds and Atmosphere absorb 20%
b) Earth surface absorbs 50%
c) Surface reflects 5%
d) Clouds and atmosphere reflect 25%
e) 30% of the Sun’s energy is not absorbed on Earth
C. Conduction
1. transfer of energy that occurs when molecules bump into one another
a) molecules are always moving
b) molecules move faster in hotter objects
2. Objects are heated up due to direct contact with an object
a) air that is in contact with the Earth’s surface is heated up
D. Convection
1. Transfer of heat by the flow of heated material
a) occurs in gases and liquids
2. Warm air
a) molecules move farther apart
b) pressure decreases
c) density decreases
d) the air rises
3. Cold air
a) molecules move closer together
b) pressure increases
c) density increases
d) the air sinks
3
4. Rising warm air and sinking cool air form a convection current
E. The Water Cycle
1. Hydrosphere
a) ALL water that is on Earth’s surface
b) 97% saltwater
c) 3% freshwater, 66% of freshwater is located in the ice caps
d) percentage of water in atmosphere is low
2. Water is constantly moving between the Earth and the atmosphere
3. The Sun provides energy for water cycle
4. Steps of the water cycle
a) evaporation: water changes from a liquid to water vapor
b) condensation: water vapor changes to a liquid, forming clouds
c) precipitation: water droplets in the clouds combine to form
larger drops that fall to Earth
IV. Movement of Air
A. Wind Formation
1. caused by the uneven heating of Earth and its atmosphere
a) causes temperature differences which causes differences in air
pressure
2. Winds move from areas of high pressure to low pressure
3. Temperature differences are caused by the Earth’s tilt in its orbit around
the Sun and Earth’s curved surface
a) Sun’s rays fall directly over equator causing higher temperatures
b) higher temperatures cause air to be less dense and rise
c) the Sun’s rays are more spread out at the poles causing it to be
cooler
d) the cooler temperatures cause air to be denser and sink
B. The Coriolis Effect
1. Caused by the rotation of the Earth
2. Causes deflection of all free moving objects
a) Northern hemisphere—deflects to the right
b) Southern hemisphere—deflects to the left
C. Surface Winds
1. Trade Winds
a) located 0o to 30o north and south latitudes
b) northern hemisphere—blows steadily to the southwest
c) southern hemisphere—blows steadily to the northwest
2. Prevailing Westerlies
a) located between 30o-60o north and south latitudes
b) northern hemisphere—blows to the northeast
c) southern hemisphere—blow to the southeast
3. Polar Easterlies
a) located between 60o-90o North and South latitudes
b) northern hemisphere—blow to the southwest
c) southern hemisphere—blow to the northwest
4
D. High Altitude Winds
1. Jet Streams
a) narrow belts of strong winds near the top of the troposphere
b) two jet streams in each hemisphere that blow from west to east
2. Seasons change the location of the jet streams
a) have a major effect on our weather
E. Daily and Seasonal Winds
1. Sea Breeze
a) occurs during the day
b) solar radiation warms the land more than the water
c) the air becomes less dense causing it to rise
d) the cooler ocean air moves onto shore
2. Land Breeze
a) occurs at night
b) land cools more quickly than the ocean water
c) the air cools over the land
d) air over land sinks and flows out over the ocean
e) the warm less dense ocean air rises
3. Monsoon Winds
a) during the winter the land is cooler than the ocean, air flows
away from land
b) winter monsoons bring long dry spells
c) during the summer the land is warmer than the ocean, air flows
from the ocean to land
d) summer monsoons bring long periods of extremely heavy
rainfall
V. Moisture and Cloud Formation
A. Humidity
1. The amount of water vapor held in the air
2. Amount of water vapor depends on temperature
a) cool air: cannot hold as much water vapor, condensation occurs
more quickly
b) warm air: can hold more water vapor, does not condense as
quickly
B. Relative Humidity
1. The measure of the amount of water vapor the air can hold at a specific
temperature
2. Saturated
a) air contains as much water vapor as it can hold
b) 100% Humidity
3. Dew Point
a) temperature at which air is saturated and condensation takes
place
b) changes depending on the amount of moisture in the air
5
C. Cloud Formation
1. Warm air is forced upward, expands and cools
2. As the air cools the amount of water needed for saturation decreases,
relative humidity increases
3. Relative Humidity reaches 100%
a) water vapor condenses around nuclei in the air
b) nuclei = dust, smoke, salt
4. The drops are so small they float in air
5. Millions of droplets form a cloud
D. Cloud Types
1. Stratus Clouds
a) form layers or even sheets in the sky
b) form when layers of cool air dip below their dew point
c) Stratus cloud fog—layers of cool air near the ground reaches its
dew point and condenses
2. Cumulus Clouds
a) puffy white clouds with flat bases
b) form when air currents rise and cool
c) can be associated with fair weather and thunderstorms
3. Cirrus Clouds
a) appear fibrous and curly
b) high, thin, white feathery clouds containing ice crystals
c) associated with fair weather but may indicate approaching
storms
E. Cloud Heights
1. Prefixes of clouds describe cloud height
a) cirro: high clouds above 6000m
b) alto: middle clouds, 2000-6000m
c) strato: clouds below 2000m
2. Cirrostratus
a) high altitude
b) made of ice crystals
c) form halos around the moon and sun
3. Altostratus
a) middle altitude
b) thick sheets of gray or blue
c) produces light continuous precipitation
F. Precipitation
1. Water Falling from clouds
a) air temperature determines if it is rain, snow, sleet, or hail
2. Rain
a) drops of water falling in temps above freezing
3. Snow
a) air temperature is so cold that water vapor changes directly to a
solid (sublimation)
6
4. Sleet
a) snow passes through a layer of warm air
b) the snow melts and then refreezes near the ground
5. Hail
a) lumps of ice
b) form in cumulonimbus clouds of a thunderstorm
c) drops of water freeze in layers around a nucleus of ice
d) hailstones grow larger as they are tossed up and down by
convection currents in the clouds
7