Post on 18-May-2015
Weather Patterns 24.5
Air Masses
Fronts
Storms
Air Mass
• A large body of air with uniform Properties
–Temp—Moisture—Altitude
• Can cover large portions of continent
What Influences Air Masses?
• Influenced by region
–Ex. Gulf of Mexico = Moist hot weather
–Ex. NW Canada = Cold dry weather
What Influences Air Masses?• Where does it form:
–Over water = moisture
–Over land = dry–Latitude = polar =
cold –Latitude = tropical /
equator = warm
Fronts• Boundary between two air masses
• Air masses move because the Jet stream pushes air masses
•Cold Front:when a cold air mass moves over a warm air mass
Warm Front:• when a warm-air mass over
takes a cold dry air mass
Fronts• Stationary Front: when two fronts
overrun each other and it
stays… – no
movement
Front• Occluded Front: when a warm
front is caught between two cold fronts/masses
Low and High pressure systems• Cyclones have a center of low air
pressure. They circulate counterclockwise. –They are associated with clouds,
precipitation and storms.• Anticyclones have a swirling center
of high air pressure–They are associated with clear skies
and calm conditions
Storms• Thunderstorm includes thunder and lightening
–Form when air rises in a cumulonimbus cloud
• Tornado is an intense windstorm in a rotating column of air that touches the ground
Hurricane is a large tropical cyclone with at least 74 mph winds
Hurricane Katrina – Aug. 2005
Predicting weather
24-6
Weather Forecasting• Meteorologists are scientists who
study weather• Doppler Radar uses Doppler effect to
bounce waves off of precipitation in the atmosphere.
• Weather stations use instruments to gather weather information.
• Computers compile and analyze weather data to help predict forecasts
Weather Maps• They show predicted temps and indicate cloud
cover, precipitation and fronts• Isotherm is a line on a map that connect points
of equal temperatures• Isobar isa line thatconnects points of equal air pressure