Thunderstorms, Hurricanes, and Tornadoes Severe Weather Thunderstorms, Hurricanes, and Tornadoes

Remember… Energy is ALWAYS trying to equalize out, dangerous events happen in the process of energy trying to find balance in the universe!

Storms Definition: any disturbance or instability of the atmosphere Formation: when a high pressure system moves into and around a low pressure system Characteristics: formation of storm clouds (cumulonimbus) and mild/strong winds

Types of Storms Ice Storms Blizzards Hail Storm Thunderstorm Hurricanes Tropical Cyclones Tornadoes

Thunderstorms Formation: hot, moist low pressure system collides with cold, dry high pressure system Characteristics: storm clouds (cumulonimbus), thunder, lightening, strong winds, precipitation Microbursts = strong wind gusts, last < 3 sec Updrafts and Downdrafts Start forming in tropical rainforests and move to middle latitudes where they meet a cold, dry front.

Microbursts and Their Effects A powerful downdraft of wind that happens only for a few seconds, normally invisible Downdraft comes out of storm clouds Discovered due to air plane crashes that were taking off during thunderstorms

Lifecycle of a Microburst

Science of Lightning Cumulonimbus clouds have positive and negative charges in them. Negative charges are at the bottom of the cloud Positive charges are at the top of the cloud Opposite Attraction between cloud and ground Cloud sends out “feeler or stepped leader” of negative charge Ground sends out a “positive streamer” Meeting in the Middle “feeler-streamer”

Fun Facts about Lightning A lightning charge contains 30 million volts at 100,000 amperes. The total energy in a large thunderstorm is more than an atomic bomb. About a hundred U.S. residents are killed by lightning every year. The Empire State Building in New York City is struck by lightning about 25 times every year. Air around a lightening bolt is heated to 54,000oF (5X hotter than the sun) Lightning bolt is usually less than 2cm in diameter

Hurricanes Formation Heat and evaporation off the water of the oceans creates a low pressure region High pressure systems moves toward the low pressure area creating heavy winds Winds flow inward towards the center and up the eye

Characteristics of Hurricanes 600 miles wide Winds range from 75-200 mph Move at 10-20mph Form over 80oF water Formation starts between 5-15o latitude north/south of equator Season in Northern Hemisphere: Atlantic June 1 to Nov 30th Pacific May 15th to Nov 30th

Hurricane Structure

Katrina (2005)

Hemispheres and Hurricanes Northern Hemisphere (counterclockwise) Coriolis Effect Path = clockwise Rotation = counterclockwise Southern Hemisphere (clockwise) Coriolis Effect Path = counterclockwise Rotation = clockwise Note: the path of a hurricane is opposite the direction the hemisphere is spinning, but the rotation of any cyclone is the same as the rotation of the hemisphere that it is in.

Formation of Tornadoes Cold, Dry Fronts collide with Warm, Moist Fronts Upper horizontal wind rotation goes vertical Column of vertically rotation air grows closer to ground out of a cumulonimbus cloud until it touches down to the ground

The Fujita Scale Fujita Scale

1884

Weather Alert System Watches: are statements that tell us that conditions are favorable for storms to form Warnings: are statements that describe storms and severe weather are happening Special Announcements/Advisors: are statements describing unusual or inconvenient weather conditions.

Questions to Answer What way does the air pressure flow in all storms? Why does it work this way? What do storms help the atmosphere do once they happen and dissipate?

Reflection Questions How well did you take notes? What was easy or hard about it? Do you think you wrote down all of the important information?