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Ch. 24 Review for Quiz
In your Journal:
1. What is humidity?
2. Explain how fog is formed.
3. Explain coalescence
4. In what form is atmospheric water found?
5. How is sleet formed?
Chapter 25
Weather
Air Mass
• A large section of air with
the same temperature
and humidity throughout.
Where do air masses obtain
their characteristic
temperature and moisture
content?
Air Mass
How do air masses move?
• Move from high pressure
to low pressure
Types of Air Masses
Types of Air Masses
• Continental Tropical (cT)
• Hot and dry
• Forms over the southwestern U.S..
Types of Air Masses
Named according to where
the air mass formed.
Maritime – formed over the
ocean
Continental – formed over a
continent
Tropical – formed near the
equator
Polar - formed near the poles
Arctic- Formed at the arctic
Polar Front
• The boundary
between cold polar air
and warmer mid
latitude air.
• 400 -600 latitude
Types of Air Masses
Maritime Polar (mP)
• Cold and humid
• Forms over cold
ocean water such
as the north
Atlantic and Pacific
Oceans..
Types of Air Masses
Continental Polar
(cP)
• Cold and dry
• Can cause a cold
snap all the way to
Florida..
Types of Air Masses
Continental Arctic
(cA)
• Very cold and dry
• Forms over
northern Canada
and the Arctic
regions.
Fronts
• Boundaries between two
different air masses.
• Changes in weather take place
along fronts!!!
Types of Fronts
Cold Front: forms
when a cold air
mass pushes under
a warmer air mass.
• Short lived and
intense rain and
maybe high wind.
Types of Fronts
Warm Front: forms
when a warm air mass
rises over and
displaces a cold air
mass.
• Has a gentle slope
• Gentle showers
Types of Fronts
Stationary Front:
this front doesn’t
move.
Types of Fronts
Occluded Front:
occurs when a cold
front overtakes a
warm front.
• Could bring any
type of
precipitation.
Occluded Front from the side
Wave Cyclone
• Low pressure area
– Brings on stormy
weather
Anticyclone
• High pressure
area
–Brings clear
dry weather.
Hurricanes
• Intense, tropical, low
pressure areas.
• Form over warm
ocean water
• Heavy rain
• Hurricane season June
to Nov.
Hurricane Katrina
Most common Hurricane tracks
Hurricanes
• 300-600 km wide.
• Eye (3) – central area
of sinking air with
high pressure; 15-50
km wide.
• Eye wall (4) – area
just outside
eye;highest winds
and heaviest rain.
Hurricanes
• Storm surge –
hurricane piles
up water and
blows it inland.
It causes the
most damage.
Storm surge
Thunderstorms
• Mostly small area storms.
• Formed by strong upward
movement of warm, moist air.
Thunderstorms
• Air mass thunderstorm – forms within a
warm moist (mT) air mass.
• Frontal thunderstorm – forms on or
ahead of a cold front.
• There are, on average, _4500___
thunderstorms /day on Earth.
Lightning
• Discharge of electricity
• Can go from cloud to cloud, cloud
to ground or ground to cloud.
Lightning effects
Thunder
• Caused by the rapid expansion of air
due to the high heat of the bolt.
• It takes 3 seconds to travel 1 km.
• It takes 5 seconds to travel 1 mile.
Tornados
• Narrow funnel shaped
column of spiral winds.
– Intense low in the center.
• Tornado season : April to
June
Tornados
• Form when rising air from
a thunderstorm meets
high horizontal winds.
• Winds cause the rising air
to rotate.
Waterspout
• Tornado over
water
• Usually light in
color.
Waterspout
Temperature
• Instrument: thermometer
• Units: degrees Fahrenheit or
Celsius
Bimetal Thermometer
• Made of 2 strips of
different metals
• Each expand at
different rates causing
bending.
• Bar curves when
heated and
straightens when
cooled.
Wind Speed
• Instrument:
anemometer
• Units: mph
Wind Direction
• Instrument
weather vane
• Units N,S,E,W
***Wind is named
from the direction
it blows from.
Direction by degrees
•
•
•
•
•
Begin with 0o
Go clockwise to 360o
East is _____.
90o
270o
180o
South is _____.
West is _____..
270o
0o
90o
180o
Doppler Radar
• Shows location and
shape of precipitation
areas.
• Detects tornados
through wind speed
and direction..
Satellites
• Provide cloud
formation pictures.
• Make high altitude
temperature and
humidity readings.
• Can show location of
hurricane eye.
Geostationary satellites
• Rotates with the Earth to
stay over one fixed
position.
• Can view nearly half the
Earth.
• Provide weather loops.
• Can track hurricanes
across the Atlantic Ocean
Forecasting Weather:
Station Model
25% cloud cover
Temp. 46
344
46
1034.4 mb
25 mph
SW wind
Isobars
• Lines drawn on a weather
map that connect points
of the same pressure.
• They indicate where high
and low pressure system
centers are.
• Winds blow from high to
low pressure.
• When lines are close
together, it’s windy..
Isotherms
• Lines drawn on a
weather map
connecting points of
the same temperature.
• They shift or bend
toward the poles in
summer and toward
the equator in winter…