Atmosphere
I. Layers of the atmosphere
A. Layers of the Atmosphere
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere*
* split into the Ionosphere
and the Exosphere
4
Mesopause
3
Stratopause
2
1
Atmosphere
B. Description of Atmosphere Layers
1. Troposphere
a. Tropo means “turning” or changing
b. extends from the earth’s surface from 12 kilometers in altitude
c. weather changes
d. COOLING TREND - temperature drops/cools as you go up
2. Stratosphere
a. extends from the Tropopause to an altitude of 50 kilometers (32
kilometers thick)
b. strong, steady winds
c. few weather changes
d. WARMING TREND - warms as you go up
e. contains the ozone layer – oxygen molecules that absorb
ultraviolet radiation
Atmosphere
3. Mesosphere (Middle Layer)
a. rises from the Stratopause to 80 kilometers (30
kilometers thick)
b. COOLING TREND - temperature falls/drops as you go up
c. Protects Earth from meteors – they burn up here
d. Coldest part of the atmosphere
• Thermosphere (Outermost layer)
a. rises from Mesopause to 300+ kilometers
b. WARMING TREND - temperature rises as you go up
(hottest layer)
c. Splits into the Ionosphere (80-550 km) and the
exosphere (above 550 km)
d. Meteors Enter here
Atmosphere
Gases in the Atmosphere (DRY AIR)
1. Nitrogen
2. Oxygen
3. Argon
4. Carbon Dioxide
5. All Others
78%
21%
0.9%
0.03%
0.01%
nitrogern
oxygen
argon
Carbon dioxide
all otheres
Atmosphere
II. Air Quality
A.Sources of Pollutants – some occur naturally, but
many are the results of human activity
1. Natural Sources – forest fires, soil erosion, dust
storms, wind carries mold and pollen, and volcanic
eruptions
2. Human Activities – most pollutants occur from the
burning of fossil fuels (cars and factories), farming,
and construction
B. Smog and Acid Rain – caused by burning of fossil fuels
C. Improving Air Quality – state and federal governments
have passed laws to reduce air pollution
Temperature
Definition - The measure of how hot or cold
something is.
A. The average energy of moving molecules. The
faster the molecules move the higher the
temperature and vice versa.
B. 3 scales
1. Fahrenheit
a. Freezing water = 32o
b. Boiling water = 212o
2. Celsius
a. freezing water = 0o
b. boiling water = 100o
3. Kelvin – based on absolute zero
K = C + 273
Temperature
C. Temperature Conversions
1. Celsius --------- Fahrenheit
9/5 (oC) + 32
2. Fahrenheit ---- Celsius
5/9 (oF – 32)
• Rules for temperature conversions
• Write the formula for each problem
• Fill in the missing information
• Solve the problem
• Round to the tenths
• Remember unit or measurement
oF
12oC
9/5 (oC) + 32
9/5(12) + 32
53.6oF
oC
50oF
5/9(oF – 32)
5/9(50-32)
10oC
Heating the Atmosphere
I.
Heat Transfer – heat is transferred in 3 different ways:
conduction, convection and radiation
*Heat is always transferred from HOT to COLD!!
A. Conduction– transfer through solids
B. Convection– transfer through fluids (liquids and
gases)
C. Radiation – transfer through empty space (from
direct heat source)
Heating the Atmosphere
II. Radiant Energy – energy from the sun (any heat source)
A. Solar energy reaches the surface of the earth by
radiation from the sun.
B. Heat is transferred through the air molecules by
convection currents.
C. Solar energy reaches the surface of the earth and
radiates back into the atmosphere – it heats the waters
by convection and the solid surfaces by conduction.
D. Not all the sun’s rays make it to the earth’s surface.
1.
2.
3.
clouds reflect about 34% of the rays back into space
the atmosphere absorbs about 19% of the rays by the
ozone layer in the stratosphere
About 47% of the rays reach the surface of the earth
Heating the Atmosphere
III. There are 2 important factors that influence the heating of
Earth’s surface:
A. Angle of insolation – the angle at which the Earth receives
the sun’s rays
1. when the sun is directly over the equator, the angle of insolation is 90o.
a. the equator receives the most amount of the sun’s energy.
b. As we move away from the equator, the angle of insolation
decreases and we receive less of the sun’s energy.
2. The greater the angle of insolation, the more DIRECT the
sunlight received by the Earth.
3. Due to the tilt of the Earth and the angle of insolation, the
Earth has SEASONS.
Heating the Atmosphere
B.
Heating the Atmosphere
Heating of land and water
A. Water and land heat up at different rates
1. water heats more slowly than land and cools more slowly
than land.
a. water heats through too many meters, while soil
only heats a few centimeters
b. water can spread the heat more evenly because it
is fluid.
c. Water is a poor conductor of heat.
2. Land heats up more unevenly than water due to different
surface textures found.
a. Land heats up quickly but releases its heat
quickly too.
b. Only the top part of the land surfaces gets heated
B. The air above land and water is heated and cooled as the
land and water below.
Atmospheric (Air) Pressure
I. What is air pressure?
A. Gravity is always pushing the layers of air surrounding the
earth down. This push is called air pressure. (weight of a
column of air)
B. The upper layers of the air push down on the lower layers of
the air. So air pressure is greater on the surface of the earth
due to this force (pressure).
II. Method of measurement
A. Air pressure is measured with a barometer – mercury or aneroid
B. Air pressure is measured in INCHES in the English – 29.92 inches
is normal
C. Air pressure is measured in MILLIBARS (mb) in the metric
system – 1013.2 mb is normal
D. Converting pressure in inches to pressure in millibars…
Pressure in inches (keep as a decimal) X 34 = Pressure in millibars (tenth)
Atmospheric (Air) Pressure
III. Isobars
A. Areas of the same air pressure are connected
on a weather maps with lines called isobars.
1.
2.
3.
work in intervals of 4 millibars
will never cross
The closer together they are the stronger the
winds and the more severe the weather
changes.
B. All pressures on a weather map are given in
millibars.
Atmospheric (Air) Pressure
IV. Types of pressure
A. Low Pressure (low millibar readings on map)
1. Often called a cyclone
2. Counterclockwise movement around the center in the
Northern Hemisphere and clockwise in the Southern
Hemisphere.
3. Type of weather is warmer and moister air (bad, stormy
weather.
B. High Pressure (high millibar readings on map)
1. Sometimes called an anticyclone
2. Direction of movement is clockwise in the Northern
Hemisphere and counterclockwise in the Southern
Hemisphere.
3. Type of weather is drier and cooler air (nice weather)
Atmospheric (Air) Pressure
C.
Predicting the Weather using Air Pressure
1.
When air pressure is rising (getting
higher), the weather is improving.
2.
When the air pressure is dropping
(getting lower), the weather is
getting worse.
3.
When the air pressure is staying the
same, the weather isn’t changing.