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AIR MASSES AND FRONTS
OCTOBER 27, 2014
• QOD: What brings changes in the weather?
• OBJ: Apply how differential heating of the Earth’s
surface and atmosphere drives convection within
the Earth’s system.
• HW: Complete the question sheet
WHAT IS METEOROLOGY?
• The study of hydrometeors and atmospheric
phenomenon
• Examples:
• Rain, Hail, Sleet, Snow, Drizzle, Graupel, Snow Pellets,
Fog
GRAUPEL
HAIL
Largest Hail Stone in U.S.
Vivian, South Dakota 8” in Diameter
WEATHER VS CLIMATE
WEATHER VS CLIMATE
• Weather is the current
• Climate is the
state of the atmosphere.
average weather
over a long period of
time.
HOW DOES THE EARTH WARM UP?
• Direct sunlight form the sun.
• Some of the Earth receives more sunlight than other
areas.
• Why is the equator warmer than the Poles?
AIR MASSES
• 5 Main types of air masses
• 5 Main types of air masses.
• Continental Tropical (cT)- Warm
and Dry
• Continental Polar (cP)- Cold and
Dry
• Maritime Tropical (mT)- Warm and
Humid
• Maritime Polar (mP)- Cold and
Humid
• Artic (A)- Colder and Drier than cP
AIR MASSES
GLOBAL WIND SYSTEMS
http://earth.nullschool.net/
FRONTS
A narrow transition
zone, or boundary,
between disparate
synoptic scale air
masses whose primary
discontinuity is density.
It is synoptic scale
along the length of
the front but
mesoscale across the
front.
COLD FRONT
Cold, dense air displaces
air and forces the warm
air up along a steep front
Usually forms vertically
developing clouds, i.e.
Cumulus, Cumulonimbus,
Supercell Thunderstorms
WARM FRONT
Advancing warm air
displaces cold air.
Gradual increase in clouds
Carries in warmer, more
humid air masses
Air rises in surface low
pressure systems.
The winds rotate
counter-clockwise
around low pressure
systems
These systems usually
bring a significant
change in weather
LOW PRESSURE
HIGH PRESSURE
Air sinks in a surface high
pressure system
Winds rotate clockwise
around a high pressure
system
Usually brings dry, quiet
weather
LET’S TAKE A LOOK!
http://www.hpc.ncep.noaa.gov/