Transcript Meteorology Basics Lecture Science 2201

Meteorology Basics Lecture
Science 2201 (chapter 18)
“Climate is what you expect,
weather is what you get.”
Distinguish between…
• Weather
• Seasons
• Climate
Chemical Composition of the Atmosphere
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Nitrogen
78%
Oxygen
21%
Argon
0.9%
Carbon Dioxide 0.03%
Trace substances
Water Vapor
Vertical Structure of Atmosphere
5 variables influence the atmosphere:
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Temperature
Pressure
Humidity
Cloudiness
Winds
Variables influencing the atmosphere…
temperature:
• Measure of heat
• Average kinetic energy
of molecules
• Weather reports give
air temperature at
ground level
Variables influencing the atmosphere…
pressure:
• High Pressure
• Low Pressure
• Region where air has
• Region where air has
piled up
stretched out
• Warmer and dryer than • Tends to rise and cool,
surrounding air
vapor condenses into
clouds
Variables influencing the atmosphere…
humidity:
• “relative humidity” –
the ratio of
amount of water vapor in air at current temp
to
max amount vapor air can hold at that temp
Variables influencing the atmosphere…
cloudiness:
• Water droplets
• Ice crystals
• Warm air rises,
cools and
condenses
(phase change)
Variables influencing the atmosphere…
winds:
• Due to differential
heating of the
earth’s surface
• Warm air rises
• Cooler air flows in
Why is it warmer near the Earth’s
equator and colder near the poles?
What patterns of global air flow occur?
Check your neighbor. Make a sketch
to explain your answer.
Global Air Circulation Patterns
Where does your weather forecast
come from?
• National Weather
Service
• World Weather
Building in Camp
Springs, Maryland
• Media weather
specialists
Weather Forecasting
• Wrong half the time?
• Many features, all are
changeable
• Nowcast  Forecast
• CNN Weather link
The Instruments
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Thermometer
Hygrometer
Barometer
Weathervane
Anemometer
The Instrument Carriers
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10,000 land-based & 7,000 ocean-based
Weather Balloons (1,000 released 2X/day)
Buoys (300 drift or are moored at sea)
Automated Weather Stations (about 1,000)
Doppler Radar
Satellites
Reading a Weather Map
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Pressure Centers
Fronts
Precipitation
Temp. Readings
Surface Winds
Winter Air Masses
• Continental Polar
• Maritime Polar
• Maritime Tropical
Summer Air Masses
• Continental Polar
• Maritime Tropical
• Continental Tropical
“Fronts” = a clash of air masses
• Cold Front
• digs in underneath
a warm air mass
• Warm air rises,
mixes with colder
air, & condenses
into clouds
“Fronts” = a clash of air masses
• Warm Front
• rides up above the
cold air
• In the rising warm
air, clouds form far
ahead of advancing
warm front
Air Masses Doing Battle link
Cloud Classification link