why does the sky turn green before a tornado?
374487
There are a couple of theories of why the sky turns green during severe weather; however moreso with hail rather than tornadoes.  Some scientists believe that hail within a thunderstorm cloud bend the light at a degree to create a green tint to the clouds.  Others also believe that the mixture of the water vapor, rain, ice, and hail within the clouds give the cloud itself a bluish tint.  Therefore when you mix the tint with the yellowing and reddening sunset, you get a green tint to the cloud.
408414
The easy answer is, of course, from the potato salad and burrito you had earlier. A more dignified answer is at Scientific American. \n\nSimply put, wind is the motion of air molecules. Two concepts are central to understanding what causes wind: air and air pressure. Air comprises molecules of nitrogen (about 78 percent by volume), oxygen (about 21 percent by volume), water vapor (between 1 and 4 percent by volume near the surface of the earth) and other trace elements. Every time we breathe, the air we inhale is composed of about the same relative ratios of these molecules, and a cubic inch of air at ground level contains about 1020 molecules. \n\nAll of these air molecules are moving about very quickly, colliding readily with each other and any objects at ground level. Air pressure is defined as the amount of force that these molecules impart on a given area. In general, the more air molecules present, the greater the air pressure. Wind, in turn, is driven by what is called the pressure gradient force. Changes in air pressure over a specified horizontal distance cause air molecules from the region of relatively high air pressure to rush toward the area of low pressure. Such horizontal pressure differences of all scales generate the wind we experience. \n\nThe areas of high and low pressure displayed on a weather map in large part drive the (usually) gentle ambient wind flow we experience on a given day. The pressure differences behind this wind are only about 1 percent of the total atmospheric pressure, and these changes occur over the range of multiple states. The winds in severe storms, in contrast, are a result of much larger and more concentrated areas of horizontal pressure change. Tornadoes are great examples. In June 2003 Tim Samaras of Applied Research Associates placed a scientific probe in the direct path of an F4 (devastating) tornado near Manchester, S. Dak. He found that the air pressure dropped by 10 percent of the total atmospheric value over the radius of the tornado. The magnitude of this air pressure change, and the very short distance over which it occurred, explains why the winds are so destructive in this phenomenon: air molecules are very quickly accelerated into the very low pressure at the center of the tornado where the water vapor contained in the air often condenses, creating the often visible "condensation funnel."
305509
tornado begins in a severe thunderstorm called a supercell. A supercell can last longer than a regular thunderstorm. The same property that keeps the storm going also produces most tornadoes. The wind coming into the storm starts to swirl and forms a funnel. The air in the funnel spins faster and faster and creates a very low pressure area which sucks more air (and possibly objects) into it. \n\nThe severe thunderstorms which produce tornadoes form where cold dry polar air meets warm moist tropical air. This is most common in a section of the United States called Tornado Alley. Also, the atmosphere needs to be very unstable. \n\nTornadoes can form any time during the year, but most form in May. But, more severe ones form earlier because the most damge is caused in April. The more north you go, the later the peak tornado season is. This is because it takes longer to warm the northern parts of the plains so tornadoes form later. \n\nMost tornadoes spin cyclonically but a few spin anticyclonically. Because there are records of anticyclonic tornadoes, scientists don't think that the Coriolis Effect causes the rotations.
44270
The funnel of a tornado is actually clear.  The only way we actually see the tornado is because of the debris that is circulating inside the funnel.  The wind speed of the tornado will not increase because of debris.  Debris can only be a hinderance to a tornado.  To help you think about this, think about a very large piece of debris, lets say a mountain.  Now while the mountain is not going to be picked up and tossed around like dirt, cows, trucks and some houses, it is still something that is getting in the way of a tornado.  The mid-west experiences far more tornadoes than any other region.  This is because they are uninhibited from forming.  Basically the more you put in the way of the funnel the more difficult it will be for that funnel (aka the tornado) to form.  To put it on a level that everyone can relate to, think of your toilet.  When you flush the toilet the water starts to swirl.  A funnel begins to appear in the water and eventually everything goes away.  What happens if there is too much TP(debris) in the way?  The funnel never forms and you get a clog.  I hope this helps.
199551
well nwhen white light goes through a prisdim, it breaks and turns into the colors of the rainbow. so when white light goes through the atmosphere, which acts like a prism, it breaks and we mostly see the blue
109227
A tornado is basically like a giant vacuum cleaner.  They are frightening and amazing all at the same time!\n\nEverything you ever wanted to know about them can be found in this excellent resource from NOAA.
885448
why is the grass green?
1052262
erm... rainbow forms when the sun shows up after a rain. this is because after a rain, the air is very humid, which means got water particles. when sunlight passes through these water particles, they are split into 7 colours, because of refraction. different colours means the colours travel in different speed. the red is the fastest, while the purple is the slowest. if the 7 colours are combined together, they will form the white, or transparent, light again. keep in mind that the rainbow only forms at the opposite of the sun.
55008
Thats a simple science question.\nRainbows almost always appear during or right after a rainstorm. The water vapor in the air forms to act as a prism. With the right angles of sunlight in relation to the water vapor, the "prism" breaks the "white" or "ultraviolet" light up into it's true colors which are red, orange, yellow, blue violet and green. I always use to remember the primary colors by using the accronym, "roybug" changing the "u" to a "v" for the violet.
466630
try this site http://www.howstuffworks.com/tornado.htm
862617
This is actually more of a coincidental event to a tornado.  When large hail is present within a thunderstorm, the refraction of light from the hailstones will occasionally cause the cloud to take on a  green hue.  This does not directly indicate the possiblity of a tornado, simply that there is large hail within the thunderstorm.  Incidently, just about all thunderstorms with tornadoes have large hail.  But one can't say because a thunderstorm has large hail, there is a tornado.
407481
According to wikipedia (as far as weather is concerned!):\n"Calm conditions, especially with clear skies, indicate the dominance of a high pressure area. Because highs are regions of descending air, they discourage the formation of phenomena typically associated with weather, such as clouds, wind, and precipitation. Calm conditions, though, may also result from a circumstance known as "the calm before the storm," in which a large thunderstorm cell to the west may be updrafting the westerly wind before it can arrive locally. This situation is readily identifiable by looking to the west — such an approaching storm will be close enough to be unmistakable."\n\nThere you have it! :-)\nhttp://en.wikipedia.org/wiki/Weather_lore
1128213
A tornado is not just wind, the fact that you can see them is either a if it drags condensation down witth them when they form (condensation funnel), or stir up dust and debris when they contact the ground. These "clouds" are actually rapidly spinning vortices (if you dont know it, look it up), that can produce winds in excess of 300 mph on the Fujita Scale (Ditto), and the stuff they can pick up and carry with them..... well, I think that about covers it.
67486
Colors in the sky occur when dust particles and debris are struck by sunlight rays and that alters their path.\n\nhttp://www.mountainnature.com/Climate/SkyColours.htm
1038584
A storm becomes a supercell about five seconds before my crazy tornado freak father calls my house and says, "you better get your a$$ over here, there's a supercell heading this way and we have to get into the cellar."  The supercell has been downgraded to a thunderstorm about five seconds before my crazy tornado freak father calls my house and says, "you're damn lucky that storm didn't spawn any tornados, your little a$$ would've been blown away. "
242740
I've heard that the sky turns a type of dirty greenish greyish colour before a severe hailstorm, or a tornado.  But I'd like to think that the sky would do that because of the types of clouds, and the absorption and reflection of light.  I've never seen it myself to say for sure. \n\nI've also been told that there are green flashes that apprear on the sea (but the sea level has to be right) around sunset.  I've never seen one of those either. Apparently, it's one of those must-see things.\n\nAnd then again, another place where greens exist is in the northern lights (Aurora Borealis)...  There are greens and they're gorgeous.  Now I've witnessed that, and it's simply GORGEOUS!!\n\nlike you said, there's always the good old rainbow!  I've seen that too :p\n\ncheers!!
499353
The first thing that has to happen is that you have to have two different patches of air moving toward each other from opposite directions, with a warm one on the bottom and a cool one on the top. \n\nThe next thing that happens is that the warm air rises. After the warm air goes up, the cool air comes down to take its place. So now the warm and cool patches of air are moving side to side and up and down. So they make a spinning patch of air along the ground.\n\nUsually when a tornado is starting, it happens during a storm. So there's lots of air moving around already. If a draft of air from the storm comes along close to the ground and then moves upwards (called an "up-draft"), it will pull the spinning air upwards.  Then comes the part that scientists don't understand quite as well. So far the spinning air is still really really wide. Somehow it gets pulled in really tight so that it makes a tornado.