National Weather Service Shreveport

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The Atmosphere

• National Weather Service Shreveport
• www.srh.noaa.gov/shv

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The Atmosphere

• Layers of the Atmosphere
• Air Pressure
• Transfer of Heat Energy
• Earth-Atmosphere Energy Balance
• Hydrologic Cycle

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The gases that makeup the Atmosphere
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Layers of the Atmosphere

• Troposphere
• Lowest Layer
• This is where we live
• 8 to 12 miles in height
• Weather occurs
• Temp decreases with height
• Stratosphere - Second lowest layer - Temp
  increases with height - Ozone (03)
  layer - Absorbs most of the damaging
  ultraviolet sunlight (UV-B)
• Mesosphere - From 30 to 53 miles up
• - Temp decreases - Majority of meteors burn up
  
• Thermosphere - Upper atmosphere 53 to 430
  miles up
• - Very few molecules

Still would feel cold
Ozone Layer
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Upper Air - Radiosondes
Radiosondes are released from the inflation
building and move up through the atmosphere (20
miles) sending back weather information along the
way.
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Launch of a Weather Balloon
The balloon with the radiosonde is launched twice
daily...at 11z and 23z (GMT)...unless otherwise
necessary.
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Air Pressure

• Density of Molecules decreases with height.
• Although the atmosphere goes up to 184 miles,
  half of the atmosphere is in the first 18,000
  feet or 3.4 miles.
• Less molecules (same composition) higher up
  makes it is harder to breath than at sea level.
• Air Pressure is converted to Sea Level Pressure
  to observe surface low and high pressures.
  (otherwise the Rocky Mts. would be always be low
  pressure and the oceans would be areas of high
  pressure).
• Pressure also dependent upon Temperature (We
  will perform an experiment on this)

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Barometers
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Draw Isotherms.
26.64 -- 902 Hurricane Katrina (2005)
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Surface Pressure
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2 Experiments

• Crunch Time (5-10 min)
• Effect of Heat on Pressure
• Items used
• 2 empty 2-liter bottles
• hot tap water
• Go with the Flow (3-5 min)
• Creating Low Pressure
• Bernoullis Principle
• Items used
• 2 empty soda cans
• level surface

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Crunch Time Experiment
Capped Bottle eventually collapsed. WHY????? -
Air inside that bottle cooled off - Cooling
takes place because the atoms inside the bottle
loose energy as they collide with the bottle side
that is exposed to the cooler surrounding
air. But why did it collapse - As atoms loose
energytheir velocity decreases resulting in a
decrease of pressure in the bottle. - Since
the pressure inside the bottle is less than
outsidethe bottle is crushed. The uncapped
bottle remains unchanged. WHY?? As air cools
inside the bottle, outside air moves into the
bottle to equalize the pressure on both sides.
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Go with the Flow

• Air flows from high to low pressure.
• The air blown between the cans created an area
  of low pressure between the cans and induced high
  pressure surrounding the cans. This caused the
  cans to move from high to low pressure. This is
  known as Bernoullis Principle.

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Transfer of Heat Energy

• Radiation
• Conduction
• Convection

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Radiation

• The transfer of heat energy by electromagnetic
  radiation.
• Earth is heated by this process. - various
  substances on earth (dirt, rocks, water,
  concrete, sand, etc.) absorb this energy and
  their heat level is raised. They transmit that
  heat through mainly convective heat transfer to
  the surrounding atmosphere, and eventually to us.

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Conduction

• The transfer of heat energy from one substance
  to another or within a substance.
• Very effective in heating metals
• Air is a poor conductor.

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Convection

• The transfer of heat energy in a fluid.
• Commonly seen in the kitchen when you see
  boiling water
• Air in the atmosphere acts a fluid

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Transfer of Heat EnergySummary

• Radiation
• Conduction
• Convection

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Thermometers

• Cotton Region Shelter
• Max and Min Thermometers
• Alcohol (min)
• Mercury (max)

• Max Min Temperature System (MMTS)
• Thermistor

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Temperature Units.
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Earth-Atmosphere Energy Balance
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The Effects of Clouds

• Nighttime clouds keep the earth warmer
• Daytime clouds keep the earth cooler

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Greenhouse Effect
The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases
in the atmosphere (water vapor, carbon dioxide,
nitrous oxide, and methane, for example) trap
energy from the sun. Without these gases, heat
would escape back into space and Earths average
temperature would be about 60ºF colder. Because
of how they warm our world, these gases are
referred to as greenhouse gases.
Prevents heat loss mainly from convection (air
movement carrying away the heat)
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Hydrologic Cycle
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Hydrologic Cycle

• Evaporation
• change of water from a liquid to a gas.
• Stepping out of a shower or swimming pool
• Transpiration
• evaporation of water from plants
• Condensation
• water vapor returns to a liquid (i.e., clouds,
  fog, mist, dew or frost)
• Precipitation
• Runoff
• Excessive precipitation that cannot be absorbed
  by the ground.

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Experiment

• Water Everywhere (10 min)
• See Hydrologic Cycle in action
• Items used
• sandwich bag
• glass jar
• hot tap water
• ice cubes

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Questions

• A sunburn is caused by which method of heat
  transfer
• A.) Radiation
• B.) Convection
• C.) Conduction
• D.) Visible Light
• Answer Radiation

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Questions

• The layer of the atmosphere where most of the
  worlds weather occurs is
• A.) Thermosphere
• B.) Stratosphere
• C.) Troposphere
• D.) Hemisphere
• E.) Mesosphere
• Answer Troposphere

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Questions

• At night, temperatures will normally be cooler
  under cloudy skies than under clear skies.
• A.) True
• B.) False
• Answer False

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Questions

• The brief cloud that forms when you exhale on a
  cold winter day was formed because of
• A.) Precipitation
• B.) Convection
• C.) Evaporation
• D.) Condensation
• E.) Runoff
• Answer Condensation

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Questions

• The hydrologic cycle is
• A.) Convection, conduction, condensation,
  Radiation
• B.) Rain, Sunshine, Condensation, Flood
• C.) Evaporation, Transpiration, Condensation,
  Precipitation, Runoff
• Answer C

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Questions

• If you feel the heat in the handle of a cooking
  pot, that heat was transferred to the handle by
• A.) Convection
• B.) Conduction
• C.) Radiation
• Answer Conduction

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Questions

• It is _____ to breath on top of a mountain than
  at sea level because there are ______ oxygen
  molecules at the summit.
• A.) easier / more
• B.) harder / more
• C.) easier / less
• D.) harder / less
• Answer harder / less

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Acknowledgments

• Jetstream website Southern Region Headquarters
  , National Weather Service
• www.srh.noaa.gov/srh/jetstream