The Atmosphere
National Weather Service Shreveport
www.srh.noaa.gov/shv
The Atmosphere
1. Layers of the Atmosphere
2. Air Pressure
3. Transfer of Heat Energy
4. Earth-Atmosphere Energy Balance
5. Hydrologic Cycle
The gases that makeup the
Atmosphere
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
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.
Launch of a Weather Balloon
The balloon with the radiosonde is launched
twice daily...at 11z and 23z (GMT)...unless
otherwise necessary.
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)
Barometers
Draw Isotherms.
26.64 -- 902 Hurricane Katrina (2005)
Surface Pressure
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
- Bernoulli’s Principle
- Items used:
- 2 empty soda cans
- level surface
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 energy…their velocity decreases
resulting in a decrease of pressure in the bottle.
- Since the pressure inside the bottle is less than
outside…the 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.
Go with the Flow
1. Air flows from high to low
pressure.
2. 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 Bernoulli’s
Principle.
Transfer of Heat Energy
1.Radiation
2.Conduction
3.Convection
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.
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.
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
Transfer of Heat Energy
Summary
1.Radiation
2.Conduction
3.Convection
Thermometers
• Cotton Region Shelter
– Max and Min Thermometers
• Alcohol (min)
• Mercury (max)
• Max Min Temperature
System (MMTS)
• Thermistor
Temperature Units.
Earth-Atmosphere Energy Balance
The Effects of Clouds
• Nighttime: clouds keep the earth warmer
• Daytime: clouds keep the earth cooler
Greenhouse Effect
The heat
greenhouse
effect
is convection
the rise in temperature
Prevents
loss mainly
from
(air movement
thataway
the Earth
experiences because certain gases
carrying
the heat)
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 Earth’s
average temperature would be about 60ºF colder.
Because of how they warm our world, these
gases are referred to as greenhouse gases.
Hydrologic Cycle
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.
Experiment
• Water Everywhere (10 min)
- See Hydrologic Cycle in
action
- Items used:
- sandwich bag
-glass jar
- hot tap water
-ice cubes
Questions
A sunburn is caused by which method of
heat transfer:
A.) Radiation
B.) Convection
C.) Conduction
D.) Visible Light
Answer: Radiation
Questions
The layer of the atmosphere where most of the
world’s weather occurs is:
A.) Thermosphere
B.) Stratosphere
C.) Troposphere
D.) Hemisphere
E.) Mesosphere
Answer: Troposphere
Questions
At night, temperatures will normally be
cooler under cloudy skies than under clear
skies.
A.) True
B.) False
Answer: False
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
Questions
The hydrologic cycle is:
A.) Convection, conduction, condensation,
Radiation
B.) Rain, Sunshine, Condensation, Flood
C.) Evaporation, Transpiration,
Condensation, Precipitation, Runoff
Answer: C
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
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
Acknowledgments
• Jetstream website – Southern Region Headquarters ,
National Weather Service
www.srh.noaa.gov/srh/jetstream