Why is there a flash at sunset?
87204
Do you mean the green flash?\nIt is there because diffraction of sunlight in the atmosphere.\nAt sunset the thickth of the air layer through whick the sunray travels, is in a maximum.
1094079
It is most likely a satellite. Several can usually be seen every evening, if you look for them. Satellites shine by reflecting sunlight, so early evening or early morning are the best times to see them, since the sun is not in the sky for you on the ground but is in the sky for the satellite at it's high altitude.
1133392
On the day of summer solstice, the sun is at it highest point in the sky, traveling the highest path across the sky. When the sun is to the side, there are shadows because a part of you is blocking the sun for something else. However, when the sun is right above you, the only thing you are blocking out from the sun is the place that you are standing in. Barely any shadows appear. The only shadows that appear are just the ones underneath you.\n\nHope this helps!
1122701
The coloration you are seeing in the sky at sunset is due to the sunlight being reflected and refracted by particles in the atmosphere.  If clouds are present, since they are mostly made up of tiny water droplets, help to refract the sunlight into a series of colorful hues.  Interestingly enough, pollution and dust have the same effect which is why desert sunsets always seem more majestic, even when there are no clouds in the sky.
539515
Moses and Campbelp have it right--the fluorescent light is closer and of larger apparent size (especially if it is a long tube!).  The sun's shadows are not perfectly sharp because it has some size.  This is the cause of the "penumbral" lunar eclipse, when the moon dims but is not fully eclipsed, as it passes through the dim but not dark portion of the Earth's shadow (the penumbra--the darkest part of a shadow is the umbra).
292254
The green flash is caused by diffraction by the atmosphere, or scattering of light at high angles (compared to the horizon).  Green happens to be very visible to our eyes, so we see it and not the other colors (this is also due to the short period of time in which this occurs).\n\nThe reason you see it in Hawaii is because you have to have an infinite horizon with no obstructions.  People see it in California all the time.
1090480
On 25th June 2006 at 05:07:26 am, exactly IST, look in the SW skies about 60 degrees. It helps if you get your watch to exactly IST from an internet time server or something. You will see a very bright flash of light.(Trust me this will really happen.)\n\nIf this looks anything like one of ur "UFO" sightings then it wasnt a UFO but sunlight reflecting off the solar panels of a Satellite.
75320
This known as a mirage.  Very simply the hot air rising from the desert surface causes light (which travels in straight lines) to be defracted (this means that the line of travel changes when moving from cold air to hot air and vice versa)  This leads to two effects.\n\nFirst is a shimmering on the ground in the middle distance which resembles sunlight glistening in water.\n\nSecondly, objects that are in the far distance can be seen to be closer than they are.\n\nThese effects can be observed on road surfaces in the right conditions during hot summer weather.
921474
Because it does not pass between where you are and the moon, or between the sun and the moon (and if it did I would think it would be so small on such a bright field any shadow would be lost in the 'blur' and distance)
471457
Because light travels faster than sound, so you see the lightning and then hear the thunder.
988375
I think it has to do with when lightening hits the surface of the water it dis purses, and weakens!!  The lightening stays on the surface!!  Have a Great Day!  MB
918082
because the sun has gone over the horizon
1025313
I was interested by this so I did a bit of research.\n\nApparently:\n\n"When the air is clear the sunset will appear yellow, because the light from the sun has passed a long distance through air and some of the blue light has been scattered away.  If the air is polluted with small particles, natural or otherwise, the sunset will be more red."\n\nSo, I suppose the answer would be a more 'orange' sunset, and possibly less vibrant.  Wikipedia says: the "Color of a sunset may be enhanced by atmospheric phenomena such as clouds, smoke and smog."
738610
I see the exact same thing. I thought something was really wrong. It looks like tv snow in the dark. When you find out, please let me know...
277115
An aurora courtain (lights in the northern or southern sky) is a phenomenon that ocurrs when our sun is in a peak of activity.\n\nEveryday, the sun, through massive explosions, sends a huge stream of charged particles to space. These particles travel at really high speeds (close to the speed of light) and, thus, hold a lot of energy. This stream is called "Solar Wind". When the sun is having a period of high activity, this "wind" is particularly strong.\n\nWhen Solar Wind reaches Earth, our planet's magnetic field changes the direction of the Solar Wind, keeping it from getting to the surface, and sending it back to space. However, at the poles, both south and north, the Solar Wind is not rejected, because of the shape of Earth's magnetic field. Instead, the stream of particles falls down to Earth describing a circular motion around the poles.\n\nThere's, then, a point in which the solar wind around the poles reaches the outer atmosphere and the falling charged particles crash with the molecules that constitute air. These collisions release energy in the form of a flash of light. The collective effect of all the different flashes creates the lights in the sky.\n\nI hope that it helps.
162449
the flash lights up the blood vessels in the retina
307165
Electric static in the air causes lightening to flash over the water.