Ch 5_2 _self made - Mater Academy Lakes High School
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Transcript Ch 5_2 _self made - Mater Academy Lakes High School
Weather
WEATHER PATTERNS
CHAPTER 5 LESSON 2
Pressure Systems
There are 2 types of pressure systems:
High-pressure system – A large body of circulating air with
high pressure at its center and lower pressure outside (air
sinks in the center)
Low-pressure system – A large body of circulating air with low
pressure at its center and higher pressure outside (air rises at
center)
Air Masses
Air masses – Large bodies of air with distinct
temperature and moisture characteristics.
They form when a large high pressure system lingers over an
area for several days.
5 types of air masses:
Continental air masses – form over land
Maritime masses – form over water
Tropical air masses – form in warm equatorial regions
Polar air masses – form over cold regions
Arctic and Antarctic air masses – for near the 2 poles (coldest
regions)
Air Masses
Fronts
Front – a boundary between 2 air masses.
4 types of fronts:
Cold front – cold air mass moves towards a warmer air mass
Warm front – lighter, warmer air moves towards the cooler,
heavier air.
Stationary front – when the boundary between 2 air masses
stalls (stays in that place for several days)
Occluded front – when a fast-moving cold front catches up to a
slow-moving warm front
Fronts
Severe Weather
Examples: Tornadoes, Drought, Hurricanes, Floods,
Sinkholes, Wildfires, Blizzards, Thunderstorms
Thunderstorms – Warm air rises due to a lowpressure system.
3 stages
Cumulus stage (cloud formations and updrafts, then downdrafts
form)
Mature stage (heavy winds, rain, and lightning)
Dissipation stage (storm ceases)
Tornadoes
A violent, whirling column of air in contact with the
ground.
Form when thunderstorms updraft begin to rotate
Measured with the Fujita scale
Tornado Alley – place in central United States that experience
most tornadoes
Hurricanes
Intense tropical storm with winds exceeding
200km/h