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11 Booming Facts About Thunderstorms

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Thunderstorms can inspire the entire range of human emotion with their vivid displays of nature's fury. Storms are used to set an ominous tone in spooky stories, even as they bring much-needed relief to parched fields or distressed humans on a hot day. These torrents are as fascinating to study as they are to watch, and as common as they are, they're actually quite complex.

1. WHAT GOES UP …

Warm, moist air is the fuel that feeds a thunderstorm the energy it needs to survive. A column of warm air quickly rising through the atmosphere is known as an updraft, and these upward winds can pack a punch. The strength of an updraft depends on how great the temperature difference is between different levels of the atmosphere. An updraft can exceed 100 mph in the strongest thunderstorms.

2. THE TOP OF THE STORM GETS SMOOSHED.

An updraft will continue skyward until the rising air is no longer warmer than the air around it. The rising air spreads out at this point, creating flat, anvil-like clouds that make a distant thunderstorm such a spectacular sight. Even more stunning are mammatus clouds, bubble-shaped formations that can develop along the bottom of anvils. Due to the strength of the storm needed to produce these vivid formations, they're often associated with severe thunderstorms.

3. RAIN DRAGS A STORM DOWN.

Once the weight of the raindrops suspended in a budding thunderstorm grows too heavy for the updraft to hold, or once raindrops fall out of the sides of the updraft, they begin falling to the ground as precipitation. The falling rain drags cooler air toward the ground, creating a downdraft, or that cool breeze you feel before and during a storm. Most downdrafts are pretty weak, but some are strong enough to cause damaging winds at the surface. A thunderstorm dies once the cool air of the downdraft cuts off the flow of warm air to the updraft, starving the storm and causing it to rain itself out.

4. THERE ARE DIFFERENT TYPES OF THUNDERSTORMS.

Not all thunderstorms are the same. There are three main types of thunderstorms. Most thunderstorms are single-cell, or a storm that pulses up, rains for half an hour, and dissipates. When that storm collapses, the wind from its downdraft can trigger more storms in a chain reaction. There are also multi-cell thunderstorms, the most common of which are squall lines. The third type of storm is a supercell, or a thunderstorm that has a rotating updraft. The twisting updraft helps supercells survive for many hours and produce more severe weather—larger hail, higher winds, and stronger tornadoes—than a normal thunderstorm.

5. HAIL BOUNCES AROUND LIKE POPCORN.

If temperatures are just right in the middle of a thunderstorm, some of the raindrops will begin to freeze as they bounce around in the updraft. The up-down motion of the newly formed hailstone will cause more liquid to accumulate on the outside of the stone, a process that causes hailstones to grow in layers like an onion. The vast majority of hail isn't large enough to cause any damage, but the updrafts in some thunderstorms are so intense that they can support hailstones the size of softballs or larger.

6. THUNDERSTORMS ARE ELECTRIFYING.

The friction between ice crystals, raindrops, and hailstones moving around in a storm can cause an electrostatic buildup between the clouds and the ground that releases its energy in a brilliant flash of lightning. Lightning is hotter than the surface of the Sun, heating the air up so fast that the shockwave radiates out in a sonic boom we hear as thunder. All thunder is caused by lightning, and all lightning causes thunder. There's no such thing as "heat lightning," a term used to describe lightning seen in the distance not accompanied by thunder. This phenomenon is simply lightning that occurs too far away for you to hear the thunder.

7. STORMS ARE PRETTY HEAVY.

Water is heavy. We look at clouds floating effortlessly through the sky and don't think about the sheer amount of weight hanging above our heads. One cumulus cloud can weigh more than 1 million pounds. When it comes to a billowing thunderstorm, though, the weight can go up tremendously depending on how much rain it's holding. We're lucky the rain doesn't all fall at once.

8. THEY BLOCK OUT THE SUN.

All of that water looming above us also has the effect of blotting out the sun. The sky gets dark before a thunderstorm because the sunshine can't make it through the vast column of water in an especially wet thunderstorm. The much-feared green sky before a storm, often thought to presage a tornado, is usually caused by sunlight refracting through both heavy rain and hailstones.

9. HUMANS CAN ACCIDENTALLY CAUSE THEM.

Humans can't control the weather, but our actions can indirectly influence where thunderstorms form. Studies have shown that increased temperatures in and around cities, due to the urban heat island effect, can trigger thunderstorms that wouldn't have otherwise formed in these areas if the city and its streets weren't there. There's also some evidence that unstable air warmed by steam released by the cooling stacks of nuclear power plants can trigger small storms.

10. IT CAN THUNDER WHEN IT'S SNOWING.

Thunder doesn't only happen when it's raining. Intense bands of snow can develop during blizzards and lake effect snow events in much the same way that a regular thunderstorm would form when it's warm out. These strong bands can produce lightning and loud cracks of thunder all while dumping copious amounts of snow in a short period of time.

11. YES, IT CAN RAIN FROGS.

There's some truth to the myth that it can rain frogs, fish, and other odd objects. If a strong tornado lofts debris high into a storm, that debris has to fall down somewhere. If a tornado sucks the water out of a pond, for example, it's very possible that the critters that used to be in the water will fall on populated areas. Hail can also form embedded with small pieces of debris like tree branches as the debris serves as a nucleus around which the water can freeze.

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Why Does the Sky Look Green Before a Tornado?
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A common bit of folklore from tornado-prone parts of the U.S. says that when the skies start taking on an emerald hue, it's time to run inside. But why do tornadoes tend to spawn green skies in the first place? As SciShow's Michael Aranda explains, the answer has to do with the way water droplets reflect the colors of the light spectrum.

During the day, the sky is usually blue because the shorter, bluer end of the light spectrum bounces off air molecules better than than redder, longer-wavelength light. Conditions change during the sunset (and sunrise), when sunlight has to travel through more air, and when storms are forming, which means there are more water droplets around.

Tornadoes forming later in the day, around sunset, do a great job of reflecting the green part of the light spectrum that's usually hidden in a sunset because of the water droplets in the clouds, which bounce green light into our eyes. But that doesn't necessarily mean a twister is coming—it could just mean a lot of rain is in the forecast. Either way, heading inside is probably a good idea.

For the full details on how water and light conspire to turn the sky green before a storm, check out the SciShow video below.

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New Contest Will Give Kids the Chance to Become Weather Channel Meteorologists for a Day
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Not every kid dreams of being an on-air meteorologist, but for young ‘uns obsessed with storm forecasts and local weather reports, a new contest presents a unique opportunity to live out their dreams. The Mini Meteorologist Contest, sponsored by Lands’ End, will give four kids a chance to present a weather report on The Weather Channel this summer.

The nationwide contest is open to future meteorologists in the U.S. and Canada ages 6 to 16. To enter, they just have to write an essay between 50 and 500 words long on why they love learning about science and weather and why they’d like to be a meteorologist for a day. Four winners will receive a trip for them and their parents to The Weather Channel’s headquarters in Atlanta. They’ll have the opportunity to report the weather for the show on July 12, which happens to be National Summer Learning Day.

The essays will be judged based in equal parts on creativity, grammar, and the entrant’s love of meteorology. The only rules for the essays are that they can’t mention any products or brands other than Lands’ End or The Weather Channel (so no essays about how L.L. Bean inspired your love of cloud formations, kids) and has to be the child’s original work. Kids who are chosen as semi-finalists will have their on-air presentation skills judged in a Skype interview.

Should they win, they’ll get an inclusive trip to Atlanta with media training, a tour of The Weather Channel headquarters, and a $500 Lands’ End gift card to get just the right weather-reporting wardrobe.

The deadline for entering is May 21. Essays can be submitted here.

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