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THUNDER STORMS AND LIGHTNING By: Kyle Clearly, Zach Weissinger, Nick Reimer STORM FACTS • Nearly 2000 thunderstorms are in progress around the world. • A typical thunder storm is 15 miles in diameter and last an average of 30 minutes. • There are 16 million thunder storms a year. FACTS CONTINUED • You can estimate how far away a storm is by counting the seconds between flashes of lightning and thunder claps. • The strongest type of thunder storm is the super cell. LIGHTNING FACTS • The odds of becoming a lightning victim in the U.S. in any one year is 1 in 700,000. • The odds of being struck in your lifetime are 1 in 3,000. • Lightning is five times hotter than the surface of the sun. LIGHTNING FACTS CONTINUED • A lightning flash is no more than one inch wide. • A stroke of lightning moves 62,000 miles per second, one third the speed of light. • Power failures caused by lightning strikes cost utility companies as much as $1 billion annually. VOCAB • Stepped Leader: The difference in positively and negatively break down and a branch channel of partially charged air is formed between the two charged regions. • Return Stroke: The stepped leader generally moves from the center of the cloud toward the ground. When it nears the ground a branch channel of positively charged particles rushes upwards to meet it. VOCAB CONTINUED • Super cells: Severe thunderstorms can produce more violent weather conditions that can develop into selfsustaining, extremely powerful storms. • Downbursts: Strong winds exceeding speeds of 160 Km/h can cause violent downdrafts that are concentrated in a local area. HOW THUNDER STORMS ARE FORMED • For a thunder storm to form it needs three conditions. 1. A source of moisture. 2. Lifting of the air mass. 3. And an unstable atmosphere. • Convention can cause a cumulus to grow into a cumulonimbus cloud. Cumulonimbus clouds conditions are the same that produce thunderstorms. TYPES OF THUNDERSTORMS • Air-mass thunderstorms: When air rises because of unequal heating of Earth’s surface within one air mass. There are two kinds of Air-mass storms. • Mountain thunderstorm: Air mass rises by orographic lifting which involves air moving up the side of a mountain. • Sea-Breeze thunderstorm: Local air mass thunderstorms that occur because land and water stores release thermal energy differently. Occur along coastal areas in the summer. • Frontal Thunderstorm: Produced by advancing cold fronts and more rarely warm fronts. In cold fronts cold air pushes under warm air which is less dense, rapidly lifting it up a steep cold front boundary which produces a thin line of thunderstorms. LIGHTNING • Lightning is the transfer of electricity generated by rapid rushes of air in cumulonimbus clouds. • Sheet Lightning: is reflected by the clouds. • Spider Lightning: Crawls across sky for up to 150 Km. • Ball Lightning: A hovering ball about the size of a pumpkin that fizzles or bangs. THUNDER • A lightning bolt heats the surrounding air to about 30,000 °C. • The thunder you hear is the sound produced as superheated air rapidly expands and contracts. • Sound waves travel faster than light waves, so you hear it before you see it. SAFETY PRECAUTIONS • To avoid being stuck by lightning, squat low to the ground on the balls of your feet. • Duck your head and make yourself smallest target. • Avoid hiding in Small sheds, isolated trees, and convertible automobiles. QUESTIONS • What is the strongest type of thunder storm? A. Super cell Storm. B. Single cell Storm. C. Multi cell Cluster Storm. • How many times hotter is lightning than the sun? A. 2x hotter. B. The same heat. C. 5x hotter. • What causes thunder? A. Lightning. B. Rain. C. Wind. • How hot is lightning? A. 30,000 °F B. 54,000 °F C. 75,000 °F • What should you do if your caught outside in a thunderstorm? A. Stand in the middle of the field. B. Seek out shelter. C. Hide under a tree. ANSWERS 1. A 2. C 3. A 4. B 5. B http://www.youtube.com/watch?v=w3QaAVpzedA