Precipitation forms when water droplets or ice crystals become too heavy to remain suspended in the atmosphere and fall to the ground. Different types of precipitation include rain, freezing rain, sleet, hail, and snow. Thunderstorms form due to strong updrafts of air and can produce heavy rain, hail, strong winds, thunder, and lightning. Lightning is caused by a buildup of electric charges within storm clouds. Tornadoes are rotating columns of air that extend from thunderstorms to the ground with wind speeds over 50 mph. Hurricanes begin as large thunderstorms over tropical oceans and derive their energy from warm ocean waters.

1. PRECIPITATION & SEVERE WEATHER

2. Precipitation Rain microscopic ice crystals or water drops combine and become too heavy to stay suspended ice crystals melt into rain as they fall through warmer layers of atmosphere Freezing Rain rain that freezes soon after hitting the ground requires warm air mass above freezing ground temperatures

3. Hail gusty winds blow rain upwards, freezing them as strong winds repeatedly lift the droplets up, more ice gathers on them Sleet raindrops that freeze as they fall through a layer of freezing air below

4. Snow ice crystals grow too heavy to remain suspended stay frozen from cloud to ground level grow larger when temps. are near freezing level colder temps. produce smaller, powdery flakes

5. Thunderstorms Begin with a strong updraft of air caused by cold front or any warm & moist air mass with cooler air around Towering cumulonimbus clouds can reach up to tropopause & flatten into anvil shape Heavy rain, sometimes hail, gusty winds, thunder & lightning Storms form & dissipate quickly (30-45 min.) video link

6. Lightning Electrons are picked up as falling ice crystals glance off other ice & rain drops negative charges build up at bottom of storm cell positive charges left behind at the top of the cloud Air becomes ionized by strong electrical fields in clouds

7. Stepped Leader jerky, stepwise movement of negative charges towards earth Return Stroke positive charges rush up to meet the negative charges brightest, hottest and loudest part of the lightning strike

8. Cumulus Clouds

9. Sheet Lightning between or within clouds

10. Lightning bolts up to 1 billion volts electricity 5x's hotter than sun's surface kill 2,000 people each year Thunder extreme heat causes air to rapidly expand and vibrate light travels faster than sound

11. Tornadoes U.S. has most tornadoes in world ~ 1,000 each year in U.S. most likely to occur April-June in late afternoon/evening wind speeds of 50 - 300+ mph Tornado Alley prime geographical area for twisters (centered around Texas, Oklahoma, and Kansas)

12. An updraft forms from cold front moving south Cumulonimbus storm clouds form as warm/moist air meets cold/dry air Wind from another direction causes rising air to rotate

13. Fujita Scale F0 to F5 to rate intensity and destructiveness of a tornado

14. Waterspout tornado over water Dust devil smaller, weaker version of a tornado (dry, not humid)

15. Hurricanes Begin as huge thunderstorms over tropical seas Rotation due to Coriolis effect Rated by meteorologists tropical disturbance tropical depression (23+ mph) tropical storm (39+ mph winds) hurricane (74+ mph) Path of Hurricane Andrew 1992

16. Eye center of hurricane low pressure center about 10 miles wide calm winds, sunny skies Rain Bands lines of thunderstorm cells rotating around the eye spiral slowly inward, becoming more intense near the eye

17. Extend up to 600 miles across Move 10-20 mph (over water), pushed by prevailing winds Weaken over land into thunderstorms (lack of warm/moist air) Categorized based on wind speed and destructiveness

18. Damage from: high winds (up to 200 mph) storm surge flooding (ocean levels 25 ft above normal) caused by high winds & hurricane eye's low pressure "bulge"