Transcript Weather - Jamestown School District

Weather
How Cold Will it be Tomorrow?
Heat Transfer
• As temperature rises, the energy within a
molecule also increases
• Radiation-direct transfer of heat energy by
electromagnetic waves
• Conduction- direct transfer of heat from one
substance to another that it is touching (metals)
• Convection-heat is transferred through a gas or
liquid (causes heating of atmosphere)
Heat Transfer - Conduction &
Convection
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Heat Transfer - Radiation
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Air Pressure
• Increase elevation =
decreased air pressure
– Air pressure drops 10 mm
for every 125 m rise
• Increased water vapor =
decreased air press.
– Water molecules are
lighter than other gases
• Increased temperature =
decrease air press.
– Increased temp= molecules
spread out
Earth’s Atmosphere
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Barometer
• Barometer is the
instrument that is used to
measure air pressure
• High Pressure system
brings nice weather.
• Low Pressure system
brings precipitation and
change in weather.
Air Fronts
• A front is a boundary
between 2 air masses
• Cold front- forward edge of a
cold air mass
• Warm front - forward edge of
a warm air mass
• Stationary front- air masses
that do not move
• Occluded front- a warm air
front is trapped between two
cold fronts
Fronts
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Precipitation
• Precipitation occurs
when water
condenses
• Types of
precipitation
– Rain, snow, sleet, hail,
fog
Moisture - Water Cycle
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Clouds
• Clouds form when water
droplets and ice form
around dust and other
particles in air
• Types of Clouds– Cumulus (big/puffy)
– Stratus (flat, sheet-like)
– Cirrus (light/feathery)
Clouds
Dew Point
• Dew Point is the
temperature at which
condensation takes place
- air becomes saturated
• As air cools, it cannot
hold as much water
Humidity
• Humidity- the amount of water
vapor in the air
• High humidity = large amounts
of water in air (low= small amt)
• Air can hold more water when
it is warm because the particles
are further apart
• Saturated: when the air is full
and cannot hold anymore
water
Lake Effect Snow
• LES - occurs when land near Lake Erie and Lake
Ontario freezes faster than the lakes (warmer air over
water, cooler air over land)
• Usually occurs within 40 km of lake
Weather Maps
• Meterologists use computers and satellites to predict
weather patterns
• Map symbols include:
– Warm/cold fronts
– Wind speed/direction
- Air pressure (isobars)
- Cloud cover symbols
Weather Prediction
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