| Thunderstorms begin to form when a strong updraft of warm, moist air develops in an unstable area of the atmosphere. Moisture condenses as the clouds grow to heights of 40,000 feet or more. Rain, snow, and even hail, are falling within the cloud and are creating powerful downdrafts of cold air from high altitudes. Soon thereafter, streaks of lightning flash across the sky, thunder rumbles, and a heavy downpour begins. The rainfall slows down, the winds calm, and the storm ends almost as quickly as it begins.
FUN-FACT: Astraphobia is a fear of storms, keraunophobia is the fear of lightning, and brontophobia is the fear of thunder.
| LIGHTNING |
| It is not entirely understood how lightning is formed, but a positive charge builds up at the top of the cloud and a negative charge is concentrated near the base. This negative charge is attracted to positively charged ground beneath the cloud. When enough voltage builds up, a two-part stroke of lightning occurs. First, a series of faint leader strokes zigzag down from the cloud. Electrically charged streamers flare up from the groud, and when the two meet, an electrical pathway is created between earth and sky. A powerful current of electricity then travels up this pathway into the cloud. This second return stroke produces the flash we see as lightning.
|  |
FUN-FACT: A single stroke of lightning lasts for only a few millionths of a second, but delivers enough energy to run a 100 watt light bulb for three months.
| THUNDER |
| The temperature of a streak of lightning reaches 27,000°F or more- hotter than the surface of the sun. These temperatures also heat up the air along a stroke of lightning. The heated air expands so violently that it generates the shockwaves we hear as thunder. A nearby stroke of lightning produces an explosive thunderclap. A more distant stroke produces a drawn-out rumbling, because the sound waves are bounced in the atmosphere and off landforms.
FUN-FACT: Since light travels fast than sound, it is possible to determine how far away lightning has struck. Counting the seconds between the visible flash and the rumbling thunder, then dividing by 5, will give you the approximate distance in miles from the lightning stroke.
| SAFETY |
- Get indoors.
- Don't swim outdoors.
- Stay in the car if a sudden storm comes up.
- Don't use a tree as shelter.
|
| | |
