do now: what countries do you think are most often hit...
TRANSCRIPT
Notepack 40 • Aim: Major Storms
• Do Now:
What countries do you think are most often hit with hurricanes?
Review: Air Masses
• cA – continental Artic, dry, very cold
• cP – continental Polar, dry, cold
• cT – continental Tropical, dry, warm
• mP – maritime Polar, wet and cold
• mT – maritime tropical, wet and warm
Review: Fronts
Cold air mass moves in, heavy
rains
Warm air moves in, light rain
Two different air masses pushing
against each other, many days of
rain
Two air masses in the same
direction, warmer air mass gets
pushed up, heave rains
The Cyclone • A Cyclone is a storm that is formed by a low pressure
system that has a counterclockwise rotation of air in the Northern Hemisphere.
• Cyclones rotate in a clockwise rotation in the southern hemisphere Due to the coriolis effect. Called Typhoons.
• Hurricanes and Tornadoes are considered cyclones.
• Cyclones pull warm air that is close to the ground to its center; this air it then sucked up towards higher altitudes.
• Heavy rain and strong wind are associated with cyclones.
Anticyclones
• Anticyclones are areas of high pressures that rotate in a clockwise direction (counter clockwise in the Southern hemisphere)
• Anticyclones pull cool air from the upper atmosphere to its center; this air it then pushed outwards away from the center.
• Calm and clear weather are associated with anticyclones.
Cyclone vs. anticyclone
Cyclone vs. anticyclone
HURRICANES • Hurricanes are
massive storms.
• 100’s of miles wide and can affect can affect many states at the same time.
• They bring high winds, heavy rain and coastal flooding.
• Also known as a typhoon in the pacific.
Parts of a Hurricane
• Hurricanes have two major parts:
– The rain bands or arms
• This is the largest part of the hurricane.
• Heavy rain
• Wind speed varies - strongest toward the center
– The Eye
• The center of the storm
• The low pressure location
• Very calm - Sunny
How do Hurricanes Form? • Hurricanes form as the results of a
very low pressure over warm ocean water.
• These low pressure areas form at the tropic latitudes (Between 20-30 degrees North latitude) during the summer.
• The warm air causes the ocean water to evaporate.
• This warm, wet air rises causing the air to be less dense (low air pressure).
How do Hurricanes Form? (cont)
• As this hot, humid air rises, it begins to rotate.
• Since this is a low pressure centers the air will be moving towards the center and spinning in a counter clockwise direction called a cyclone.
• The more the pressure drops, the faster the wind will blow. (Wind speeds of 70 miles per hour or higher)
What factors are needed for hurricanes to form?
• Warm water
• Hot air
• A low pressure area
• Winds of over 70 mph
Why are hurricanes dangerous?
• High winds
– Winds can knock down trees, power lines and buildings.
– The wind can carry debris which can crash through windows and walls causing lots of damage.
• Floods
– Hurricane brings lots of rain which could flood streets.
– The high winds can push ocean water onto land, flooding coastal areas. This is a storm surge.
What is a storm surge? •A storm surge is when high winds push
ocean water on to shore.
•Very dangerous during high tides.
How do Hurricanes move? • Since Hurricanes need warm
water, they usually follow warm ocean currents which East to West.
• But because the North and South American continents block these current path, the currents travel up along the east coast side of the US.
• Because of this, hurricanes can travel to New York.
• Once over land, the Hurricane begins to die. (no water, means no hurricane)
Tornadoes • Tornadoes are very strong
storm.
• They produce very strong winds. (can be over 200 miles per hour)
• They form very quickly and disappear just as quick.
• They a usually associated with strong thunderstorms.
How are tornadoes formed? Tornado are formed when
warm, humid air from the Gulf of Mexico collides with cooler, drier air from Canada. These collisions create the huge thunderstorms that can form tornadoes.
• This collision also produces an extremely localized (small area) low pressure center.
• This small low pressure center produces a counterclockwise spin of air.
• If the spin is fast enough a tornado will form.
Water Spout • Water spouts are
tornadoes that form over a body of water.
• They are not as strong a tornados but can still have very strong, localized winds.
• They are usually thinner than a tornado.
• Sometimes tornados will move onto water becoming a water spout.
Vocabulary
• Prevailing westerlies- typical west wind at
our latitude. (40-50)
• Trade winds- prevailing wind from east
below Florida’s latitude
• Jet stream- high altitude, high speed “river
of air.”
WEATHER RULES
• RULE 1: air flows from high to low pressure
• Rule 2: warm air rises
• Rule 3: Moist air has a lower pressure than dry air
PREVALING WIND PATTERNS
OTHER Types of Cyclones:
Tornado- a small, compact storm with strong winds.
AKA:
Twister
Willy-Willy (Australia)
Hurricane far off shore Rough surf
hundreds of
miles away.
Storm Surge
Hey! Let’s
check out the
storm!
Hurricane Tracks
CCW
CW CW
CCW CCW
