Heating the Atmosphere

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Heating the Atmosphere
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Electromagnetic Waves

• The sun is the ultimate source of energy that
  creates our weather.
• You know that the sun emits light and heat as
  well as the ultraviolet rays that cause a
  sunburn.

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Electromagnetic Waves

• These forms of energy are only a part of a larger
  array of energy called the electromagnetic
  spectrum.
• All radiation, whether X-rays, radio waves or
  infrared waves, travel through the vacuum of
  space at 300,000 kilometers per second.

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• Only 7 of the light energy received by the earth
  is visible light.

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Electromagnetic waves are classified

• by their wavelengths the distance from the
  crest of one wave to the crest of the next wave.

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Heat transfer
Three mechanisms of energy transfer as heat are
Conduction Convection Radiation All three
processes happen simultaneously in our
atmosphere. These mechanisms work to transfer
energy between Earths surface (both land and
water) and the atmosphere.
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Heat transfer

• Conduction the movement of heat from molecule
  to molecule through molecular activity
• Heat flows from the higher temperature matter to
  the lower temperature matter
• Metals are good conductors
• of heat air is a poor
• conductor of heat.

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Heat transfer
Because air is a poor conductor, conduction is
important only between Earths surface and air
directly in contact with the surface. For our
atmosphere, conduction is the least important
mechanism of heat transfer.
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Heat transfer

• Convection the movement of heat by circulation
  within a substance
• Much of the heat transfer that occurs in the
  atmosphere is convection
• Convection takes place in fluids where the
  molecules can move freely.
• The atmosphere behaves like a fluid

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Heat transfer

• example of convection a pot of boiling water

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Heat transfer

• Radiation the release and transfer of energy in
  wavelengths of heat and light through space.
• Solar Energy reaches the Earth from the sun by
  radiation
• There are actually 4 laws that govern radiation.

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1 All objects, at any temperature, emit radiant
energy. Not only hot objects like the sun, but
colder objects like the Earth (including its
polar ice caps) continuously emit energy.
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• 2. Hotter objects radiate more total energy per
  unit area than colder objects do.

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• 3. The hottest radiating bodies produce the
  shortest wavelengths of maximum radiation

• The sun, at 6000C, radiates at .5 micrometers.

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When radiation strikes an object, there are
usually three different results.

• 1. Some energy is absorbed by the object. When
  radiant energy is absorbed, it is converted to
  heat and causes a temperature increase.
• Like what??

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When radiation strikes an object, there are
usually three different results

• 2. Substances such as water and air are
  transparent to certain wavelengths of radiation.
  These substances transmit the radiant energy.
• In other words Radiation goes THROUGH the object

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When radiation strikes an object, there are
usually three different results

• 3. Some radiation may bounce off the object
  without being absorbed or transmitted.
• Thus being scattered

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• This scattering is why the sky is blue

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• and the sunsets are often red
• (what do you think is the meaning of Red sky
  at night, sailors delight red sky in the
  morning, sailors take warning

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Heat Budget of the Atmosphere
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• When it reaches the Earth, some is reflected back
  to space by clouds, some is absorbed by the
  atmosphere, and some is absorbed at the Earth's
  surface.
• Since the Earth is much cooler than the Sun, its
  radiating energy is much weaker (long wavelength)
  infrared energy.

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Heat energy from the earth can be trapped by
clouds leading to higher temperatures as compared
to nights with clear skies.

• The air is not allowed to cool as much with
  cloudy skies.
• Under partly cloudy skies, some heat is allowed
  to escape and some remains trapped.
• Clear skies allow for the most heat to escape
  cooling to take place.

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• About 50 of solar energy reaches the surface and
  is absorbed.
• Most of THIS energy is reradiated.
• The atmosphere absorbs the longer wavelengths
• Larger molecules, like water vapor and CO2,
  absorb the energy
• This energy is transformed into molecular motion
  rise in temperature

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• Simplified diagram of the heating of the
  atmosphere

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Albedo (Al-bee-dough)

• The percent of radiation returning from a surface
  compared to that which strikes it
• When an object reflects most of the light that
  hits it, it looks bright and it has a high
  albedo. 
• When an object absorbs most of the light that
  hits it, it looks dark.   Dark objects have low
  albedos.

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• Clouds albedo is near 60
• Snows albedo is up to 95 percent
• Waters albedo is (on average) about 10
• Average albedo for earth and clouds is about 30

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Conditions of the Air

• Temperature amount of hotness or coldness
  relative to something else
• Thermometer an instrument that measures
  relative hotness or coldness
• Dew Point temperature The temperature at which
  air becomes saturated
• Isotherm a line connecting places with equal
  temperature on a weather map
• Temperature scales
• 1C 1.8F or 1F 5/9 C

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Celsius to Fahrenheit and Fahrenheit to Celsius
Formula C  x  9/5 32 F (F 
-  32)  x  5/9 C
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For Example

• Convert 37C to Fahrenheit.
• 37C x  9/5 32 98.6F
• OR
• 37C x 9  32 98.6F 
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• Convert 98.6F to Celsius.
• (98.6F  -  32)  x  5/9 37C
• OR
• (98.6F - 32) x 5  37C 
• 9

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Conditions of the Air (cont.)

• Air pressure - the downward pressure exerted by
  the weight of the overlying atmosphere or the
  weight of the atmosphere per unit AREA.
• Barometer an instrument used to measure air
  pressure
• Measured in inches of
• mercury in a column
• Or millibars (metric
• conversion)
• Average air pressure
• at sea level is 1013 millibars

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• What do you notice about the relationship between
  air pressure and volume?

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• What do you notice about the relationship between
  air pressure and temperature?

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• What do you notice about the relationship between
  volume and temperature?

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Pressure depicted on a weather map

• Isobars lines con-necting points of equal
  pressure

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Isobars on the vertical
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Note the density of molecules close to the
surface
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Measurement of the Atmosphere

• The condition(s) of the atmosphere is measured by
  the radiosonde

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• A radiosonde is a small instrument package
  tethered to a weather balloon.
• take a vertical profile of the atmosphere as the
  balloon ascends to altitudes up to 115,000 feet.
  
• the data is relayed by radio transmitter to a
  computer at the surface

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• Launch of a weather balloon off an aircraft
  carrier

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• photo shows the weather balloon bursting at
  99,712 feet

http//www.brothers-brick.com/2008/08/06/mindstorm
s-nxt-fans-launch-lego-into-space-via-weather-ball
oon/
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Synoptic Map

• Station models group of symbols depicting
  weather conditions
• Isobar line of equal pressure
• a. show locations of High or Low pressures
• b. close lines mean strong winds
• c. lines far apart mean gentle winds

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Station Model

• how meteorologists can put a lot of information
  in a small area

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Water in the atmosphereWater Vapor

• Humidity the amount of water vapor in the air
• Relative humidity the actual amount of water
  vapor in the air compared to the greatest amount
  the air can hold

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Water in the atmosphereWater Vapor

• Saturated to be completely filled with water
  vapor
• Psychrometer an instrument to measure relative
  humidity
• Hygrometer an instrument used to measure the
  airs humidity

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Precipitation

• water or ice that condenses in the air and falls
  to the ground as
• Rain- liquid water that falls to the ground
• Snow - ice crystal flakes water vapor in the
  atmosphere that froze into ice crystals and falls
  to the ground in the form of flakes
• Sleet -partially melted grains of ice
• Hail - pellets made of layers of ice and snow
• Freezing rain rain that freezes into ice as it
  hits the ground

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Weather Advisories

• Weather WATCH predictions about approaching
  severe weather
• Weather WARNING specific severe weather
  conditions have been actually observed by a
  person or verified by a computer

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• http//www.sleepingdogstudios.com/Network/Earth20
  Science/ES_17.2_files/frame.htm