Severe Weather Notes and information

BIG IDEA The root of all weather is the Sun, which heats the Earth. The heating is uneven, because of night and day, because different surfaces (such as rocks and trees) absorb and reflect sunlight in different amounts, and because sunlight hits the equator more directly than the poles. Uneven heat creates pressure differences, and wind flows between areas of high and low pressure.

Thunderstorms

storms Thunderstorm is storm with thunder, lightning, heavy rains and strong winds; form within large cumulonimbus clouds; usually form along a cold front but can form within an air mass. Click on the links below: Thunderstorm Formation Animation Real Thunderstorm Animation

How they Form Form within large cumulonimbus clouds. Warm air is forced upward by a cold front. Warm air rises extremely quickly; cools and condenses just as fast to form huge dense clouds (anvil).

Characteristics: Lightning and Thunder Positive and negative charges build up in clouds. Lightning is a sudden spark as charges jump from one cloud to another. Thunder is caused by the rapid heating of the air. +++ ++ - - - - - ++ ++ - - - + - - - - - - - - - +++ ++ - - - - - ++ ++ - - - + - - - -

Characteristics: When and Where? Most Likely to form on hot humid days Spring and Summer Occur in areas where cold fronts are common (just about anywhere) **To be “severe” it must have ONE OR MORE of the following: Winds at least 57.5 mi/hr Hail ¾” or larger Tornado

Thunderstorm Safety Avoid metal objects Try not to be the tallest object in an area Find a low area away from trees, fences and poles. Make yourself as small as possible. Stay out of the water Avoid touching electrical appliances or phones.

Interesting Facts You can calculate your distance from a storm. # of sec. / 3 s/km = distance(km) Lets Try… At any given time there are 1800 storms on Earth. 80 die from lightning each yr. Winds can exceed 160 km/hr. Causes hundreds of millions of $$ in damage each yr.

Tornadoes

Tornado Wind Patterns Animation storms A tornado is a rapidly whirling, funnel-shaped cloud that extends down from a storm cloud; the very low pressure and strong winds can cause great damage to people and property. Tornadoes are likely to form within the frontal regions where strong thunderstorms are also present. Click on the link below to do the animation: Tornado Wind Patterns Animation

How They Form Develop in low heavy cumulonimbus clouds. Warm air rises so fast that it creates an updraft. As it rises it begins to rotate At the same time, cold air drops just as fast and creates a downdraft Updraft grows more narrow, and spins faster.

Another view Play Animation

Where and When (characteristics) Occur in Spring or Summer Associated with T-Storms Tornado Alley….

Tornado Alley The Great Plains… Why?.......... Warm, moist air from the Gulf rises and meets with cold dry air from Canada.

Interesting Facts: Wind speeds can reach up to 480 km/hr. More common in US than any other country Biggest threat is flying debris

Tornado Safety Tornado watch = they are possible Tornado Warning = one has been seen Go to the basement of a well-built building. Stay away from windows and doors Lie under a steady piece of furniture Duck and cover If outside: lie in a ditch

Now….Some cool pictures

Hurricanes

storms A hurricane is a low pressure tropical storm that forms over warm ocean water; winds form a spinning circular pattern around the center, or eye, of the storm. The lower the air pressure at the center, the faster the winds blow toward the center of the storm. Click on the link to watch the video: Hurricanes 101 Video

How they form Begins over warm water in a low pressure area Warm humid air from ocean water rises to form clouds Winds spiral inward toward low pressure.

When and Where: Characteristics Forms in the summer and fall over the oceans Winds can be as strong as 320 km./hr. Last a week or more Loses strength after reaching land. Play animation

Special Features: Characteristics The eye is the center of the hurricane which has very calm weather. Storm Surge huge rush of water that arrives with hurricanes.

Saffir-Simpson Scale category 1: minimal (119-153 km/h) category 2: moderate (154-177 km/h) category 3: Extensive (178-209 km/h) category 4: Extreme (210-250 km/h) category 5: Catastrophic (over 250 km/h)

Hurricane Safety Hurricane watch = conditions are possible Hurricane warning = conditions are expected. Evacuate the area Move to the interior of a building away from windows. Stay well above sea level

Interesting Facts Typical hurricane is 600km. Across (Andrew was only 60 km) Hurricane Andrew cost over $25 bill. Andrew was only 1 of 3 that hit the US to be classified as a category 5 hurricane In the Pacific it is called a typhoon

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