Download Atmosphere pt. 3

Air Masses
Large bodies of air
formed when a body of air hangs
over a region and takes the
temperature and humidity from
that region
5 types
1. continental
Polar
•cold and dry
•effects
Michigan the
most
• 2. maritime Tropical
• warm and moist
• Effects Florida
• 3. continental
Tropic
• warm and dry
• 4. maritime
Polar
• cold and moist
• 5. continental
Artic
• Very cold and
dry
Diagram
FRONTS
Boundary between two air masses
4 types:
1. cold
2. warm
3. stationary
4. occluded
COLD FRONT
• Cold air mass
pushes a warm air
mass
• steep slope
• brings
thunderstorms or
severe weather
Cumulonimbus
clouds
WARM FRONT
• Warm air mass
pushes a weaker
cold air mass
• little temperature
change
• brings steady rain
nimbostratus clouds
STATIONARY FRONT
• When two air
masses meet but
cannot push each
other
• steady rain for
days
OCCLUDED FRONT
• A cold front overtakes a warm
front
• warm air forced up rapidly
• LOW pressure
• and storms
L
Causes of wind
• 1. Uneven heating of the Earth
creates:
2. Differences in air pressure
creates:
High pressure area and low pressure
area
All winds blow from a High pressure to
a Low pressure
3. CONVECTION CELLS
• Warm air rises; cool air sinks
4. CORIOLIS EFFECT
• Caused by the rotation of the earth
• Earth rotates on the average 750mph
– faster at the equator
– Causes winds to be deflected to
the right in the
– Northern Hemisphere
WESTERLIES
Blows from the west to the east
Effects the weather the most in the US
TRADE WINDS OR EASTERLIES
Blow from the east toward the equator
Isobars- line that
connect areas of
equal air pressure
Isobars and relative wind speed
• Isobars- line that connect areas
of equal air pressure
– Close isobars=high wind speed
Rules:
• Low Pressure System: Increased
cloudiness, winds, temperatures,
and chance of precipitation.
• High Pressure System: Indicates
clear, cooler temperatures with
reduced chance of precipitation.
WHICH
HASsky's
HIGHER
WIND
SPEEDS
Which
stateSTATE
has clear
(probably
)Texas
or
TEXAS OR MICHIGAN?
Michigan?
Cumulonimbus clouds
-Contain heavy rain, lightning, hail and wind
-Possible tornadoes
-Associated with a cold front
Two of the most important ingredients for
thunderstorm formation are instability
(unstable air) and moisture.

During a thunderstorm, the Earth's surface has
a positive charge. Because opposites attract, the
negative charge at the bottom of the thunder
cloud wants to link up with the positive charge
of the Earth's surface.



1. The electricity passes through the air and
starts it vibrating. The vibrations cause sound.
2. The lightning is also very hot and heats up
the air around it. Hot air expands and the air
gets bigger very quickly, and pushes apart the
air particles.
These vibrations are what you hear and call
thunder
THUNDERSTORM DOWNBURST


Form at the base of a cumulonimbus cloud
The formation of tornadoes is the result of
warm, moist air meeting cooler, dry air, and
creating instability in the atmosphere.

Season: spring to mid-summer

Strongest wind speeds

Ranked on the (Enhanced) Fujita Scale
FUJITA SCALE
EF-0
65-85 mph
EF-1
86-110 mph
EF-2
111-135 mph
EF-3 136-165 mph
EF-4
166-200 mph
EF-5
Over 200 mph



Cyclone over warm water
Pre-existing storm
Has an eye – low pressure in the center

Has a storm surge


Most dangerous part of a hurricane
Wall of water near the eye
Causes most destruction and loss of life
ANDREW-1992
Hurricane season June 1- Nov.30
 Tropical Depression
Wind speeds between
20 and 34 knots (23-39 mi/hr)


Tropical Storm
Wind speeds between 35
and 64 knots (40-73 mi/hr)
Hurricane
(74 mi/hr)
Wind speed greater than 64 knots

Rotation : Clockwise or Counter clockwise ?
 Counter clockwise



The eye is the center of the storm.
The eye wall surrounds the eye. The strongest
winds and heaviest rains are found in the eye
wall.
Rain bands are long, arching bands of clouds
and thunderstorms that spiral out from the eye
wall.

Hurricane season June 1- Nov.30

if it moves over land, thus depriving it of the
warm water it needs to power itself, quickly
losing strength.
?