Facts about thunderstorms
- Lightning can and often does strike the same place twice.
- The electrical forces tend to prefer tall or metallic objects,
especially if they aren't well grounded.
While a storm is in progress, there's nothing to stop a positive charge
from collecting in the same place it did before.
- Thunderstorms can occur anywhere on Earth
- The atmospheric conditions to form a thunderstorm can occur anywhere
on Earth.
Sometimes you may hear someone say "we don't get thunderstorms here."
(This myth is common in coastal cities on the US West Coast.)
Usually that means that they don't know how to recognize a thunderstorm
without seeing lightning. Many people don't.
Lightning Safety
- Lightning Safety
at the Weather Channel
- Safety info and tips.
- Thunderstorms
by the US Federal Emergency Management Agency
- Information about lightning safety for kids.
- Lightning Kills, Play It Safe
at the US National Weather Service
- Information about lightning and its dangers.
- Lightning Safety for Kids
by Sabrina (girl who was struck by lightning)
Lightning Photography and Stories
- Lightning and Severe Weather Photography
by Douglas "Lightning Boy" Kiesling
- Photographs of lightning and tips for your own photography.
- Lightning Strikes My Backyard
by Ian Kluft
- Lessons learned and photos of the tree branch removal after a lightning
strike in San Jose, California on Sept 9, 1999.
- ozthunder.com - Australian Weather and Storm Chasing
- Storm chasing diaries, photos and info from Australia by Michael Thompson
Lightning-mapping Projects
- National Lightning Detection Network
- Map plot of automatically-detected lightning across the US
- New Mexico Tech 3D Lightning Mapping System
- 3-dimensional lightning mapping research system
Cumulonimbus clouds at sunset over the North Atlantic Ocean.
(select to download: 1536x1002 728K)
Lightning in the Upper Atmosphere: Sprites, Blue Jets & Elves
General Info on Thunder and Lightning
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How does a thunderstorm form?
A thunderstorm always starts from a cumulus cloud.
Though not all cumulus clouds grow into thunderstorms.
A cumulus cloud can be recognized for its cotton-like puffy shape.
If the conditions are right, the cloud begins to grow upward.
More about the "right conditions" will be mentioned below.
In this growing stage, the cumulus cloud can become very tall.
People refer to this stage as a "towering cumulus", which
means the cloud will become a thunderstorm soon.
You can easily tell if a cumulus cloud is growing upward.
If the tops of the clouds are jagged in shape, they are not growing.
But if the tops of the clouds change to curved shapes, they have
begun growing upward.
(If you see this from on top of a mountain, that's the time to
start getting off the mountain.)
About the time that the first wispy-shaped and icy cirrus clouds form
at the top of the towering cumulus, the first lightning can occur in
the cloud. It won't necessarily be a bolt that strikes the ground.
But at this point it's a thunderstorm.
Once it starts rain from the cloud, we call it a "cumulonimbus" cloud.
That's because any cloud which produces rain has "nimbus" in its name.
In the final stage of a thunderstorm's life cycle, the rain and downdrafts
take all the moisture out of the clouds.
It basically rains itself out.
The storm dissipates from the bottom up.
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Under what conditions does a thunderstorm form?
If these "ingredients" are present together in the atmosphere,
a thunderstorm will form.
- moisture
- The clouds need moisture to form in the first place.
The more moisture available in the air, the more clouds can form.
- instability
- The air usually gets cooler as you go up in altitude -
you can easily see this when you travel up a mountain
and the air is cooler than in nearby valleys.
But the rate that it gets cooler isn't always the same.
When warm air rises, it cools. But if it's still warmer than the
air around it, it can keep rising.
This is called unstable air.
It can keep rising until it reaches an altitude where the air is stable.
- uplift
- With the other ingredients in place, anything that makes air rise
will start the growth of a thunderstorm. Warmth from sunlight shining
on the ground can do it. So can wind blowing up a mountainside.
Turbulent winds ahead of or behind a weather front can cause uplift.
Even smoke from a large fire can start this process.
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