2. Severe Weather

3. Ever touched someone after scuffling your feet on the carpet and received a mild shock? When you walk around the friction between the floor and your shoes builds up an electric charge in your body. When you touch someone else, the charge is released. You’ve experienced what lightning is like! LIGHTNING

4. Lightning is an electric current. Within a thundercloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud.

5. Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!

6. Lightning can occur between: Two clouds Earth and a cloud Two parts of the same cloud https://www.youtube.com/watch?v=h- 0gNl5f4BU HOW LIGHTNING FORMS VIDEO:

7. TORNADOES Tornadoes happen in only 1% of all thunderstorms. A tornado is a small, spinning column of air that has high wind speeds and low central pressure and that touches the ground. A tornado starts out as a funnel cloud that pokes through the bottom of a cumulonimbus cloud and hangs in the air. The funnel cloud becomes tornado when it makes contact with the Earth’s surface.

8. 75% of the worlds tornadoes occur in the United States. (Mostly in Tornado Alley). Most happen in early spring and summer when cold, dry air from Canada meets warm, moist air from the Tropics. The size of a tornado’s path is about 5 miles long and about 30 – 200 feet wide. Tornadoes have wind speeds from 75-100 mph and more violent tornadoes spin over 300 mph.

13. Most tornadoes develop from thunderstorms at the leading edge of a cold front. Why do you think this happens?

14. The cool air wedges under the warm air, which may result in wind moving in opposite directions. This movement may cause a layer of air to spin. Rapidly rising warm air can turn the spinning layer into a vertical funnel.

15. Hurricanes A large, rotating tropical weather system that has wind speeds of at least 120 km/h (75 mph) is a hurricane. Hurricanes are the most powerful storms on earth.

16. A Hurricane begins as a group of thunderstorms moving over tropical waters. Winds traveling in two different directions meet and cause the storm to spin. Because of the Coriolis Effect, the storm turns counterclockwise in Northern Hemisphere and clockwise in the Southern Hemisphere.

17. At higher latitudes, the water is too cold for hurricanes to form. Hurricanes vary in size from 160 to 1,500 km (99 to 935 miles) in diameter and can travel for thousands of miles.

18. Cross section of a Hurricane

19. A hurricane gets its energy from the condensation of water vapor. Once formed, the hurricane is fueled through contact with the warm ocean water. Moisture is added to the warm air by evaporation from the ocean. As the warm, moist air rises, the water vapor condenses and releases large amounts of energy.

20. The hurricane continues to grow as long as it is over its source of warm, moist air. When it moves over colder waters or land, it begins to die because it has lost its source of energy.

21. As the most powerful storm in the world, hurricanes cause a lot of damage when they move onto or near land. With high winds from 120 km/h (75 mph) to 300 km/h (186 mph) – hurricanes can knock down trees, destroy buildings and homes. Yet, most hurricane damage is caused by flooding associated with heavy rains and storm surges.

22. A STORM SURGE is a wall of water that builds up over the ocean because of the strong winds and low atmospheric pressure. The wall gets bigger as it reaches the shore, and it reaches its greatest height when it crashes onto the shore. Depending on its strength, a storm surge can be 1 to 8 meters high (26 ft) and 65 to 160 km long (100 miles)