why not every  cloud rains.?
454900
Well you see, not all clouds are the same: Here are some different types of clouds, that don't rain at all.\n\nCirrus Clouds\nCirrus clouds are the most common of the high clouds. They are composed of ice and are thin, wispy clouds blown in high winds into long streamers. Cirrus clouds are usually white and predict fair to pleasant weather. By watching the movement of cirrus clouds you can tell from which direction weather is approaching. When you see cirrus clouds, it usually indicates that a change in the weather will occur within 24 hours.\n\n\nCirrostratus clouds are thin, sheetlike high clouds that often cover the entire sky. They are so thin that the sun and moon can be seen through them. Cirrostratus clouds usually come 12-24 hours before a rain or snow storm.\n\n\nCirrocumulus clouds appear as small, rounded white puffs that appear in long rows. The small ripples in the cirrocumulus clouds sometime resemble the scales of a fish. Cirrocumulus clouds are usually seen in the winter and indicate fair, but cold weather. In tropical regions, they may indicate an approaching hurricane.\n\n\n"Alto" Clouds\nAltostratus clouds are gray or blue-gray mid level clouds composed of ice crystals and water droplets. The clouds usually cover the entire sky. In the thinner areas of the clouds, the sun may be dimly visible as a round disk. Altostratus clouds often form ahead of storms with continuous rain or snow.\n \n\nAltocumulus clouds are mid level clouds that are made of water droplets and appear as gray puffy masses. They usually form in groups. If you see altocumulus clouds on a warm, sticky morning, be prepared to see thunderstorms late in the afternoon.\n\n\nStratus Clouds\nStratus clouds are uniform grayish clouds that often cover the entire sky. They resemble fog that doesn't reach the ground. Light mist or drizzle sometimes falls out of these clouds.\n \n\nStratocumulus clouds are low, puffy and gray. Most form in rows with blue sky visible in between them. Rain rarely occurs with stratocumulus clouds, however, they can turn into nimbostratus clouds.\n\n\nNimbostratus clouds form a dark gray, wet looking cloudy layer associated with continuously falling rain or snow. They often produce precipitation that is usually light to moderate.\n\n\nCumulus Clouds\nCumulus clouds are white, puffy clouds that look like pieces of floating cotton. Cumulus clouds are often called "fair-weather clouds". The base of each cloud it flat and the top of each cloud has rounded towers. When the top of the cumulus clouds resemble the head of a cauliflower, it is called cumulus congestus or towering cumulus. These clouds grow upward and they can develop into giant cumulonimbus clouds, which are thunderstorm clouds.\n\n\nCumulonimbus clouds are thunderstorm clouds. High winds can flatten the top of the cloud into an anvil-like shape. Cumulonimbus clouds are associated with heavy rain, snow, hail, lightning and even tornadoes. The anvil usually points in the direction the storm is moving.\n \n\nSpecial Clouds\nMammatus clouds are low hanging bulges that droop from cumulonimbus clouds. Mammatus clouds are usually associated with severe weather.\n\n\nLenticular clouds are caused by a wave wind pattern created by the mountains. They look like discs or flying saucers that form near mountains.\n\n\nFog is a cloud on the ground. It is composed of billions of tiny water droplets floating in the air. Fog exists if the atmospheric visibility near the Earth's surface is reduced to 1 kilometer or less.\n\nContrails are condensation trails left behind jet aircrafts. Contrails form when hot humid air from jet exhaust mixes with environmental air of low vapor pressure and low temperature. The mixing is a result of turbulence generated by the engine exhaust.\n\nhope this helps :-).
440607
Since the prehistoric era. It doesnt take a genius to observe the correlation between rain and clouds. It doesnt rain when there are no clouds. Clouds disappear after a rain.
46145
Every cloud could be a tale of a man compounded with bad luck and cliched advice, a man who's world is falling apart but who's only help and advice comes from comments such as Every cloud has a silver lining/ cheer up it might never happen/ things can only get better etc. The man could then go out in search of the silver lining and possibly find it as insubstantial as the cliche, and resign himself to the fact that the world is what the world is and words of advice are only a means to stop people complaining.   - Just a thought.
659938
Why do people ask such questions?\n\nIf there is an obstacle to the flow of the air, of course it's gonna change the climate and temperatures because the air flow cannot go through mountains barriers, it will clash against it and part of it will go over it.\n\nBut the point is, if it was a cool air flow in hot summer ( happens sometimes but you'll have to ask another question on this subject), the sky will get all the cool air but because of the mountains barriers the lower part of the flow will not go through, that is how we get rain on hot days!
249475
Clouds are flat on the bottom because of the condensation level. There is a point as you climb in altitude (not always the same) where the moist rising air reaches the dew point (saturation point) and condenses onto tiny particulate matter in the air. It's nearly flat looking because of the temperature change as you climb is nearly parallel to the ground. Sort of even. Not quite.
1116902
The mechanism of Cloud formation is still not understood. Researchers are now applying Chaos Theory in the study and modelling of cloud behavior.\n\nWe "see" clouds only when the high moisture regions are sufficiently close to refract and reflect light. Actually they are highly dynamic systems.
36815
From the National Weather Service:\n\nWhen we talk about rainfall, we usually refer to it as being either showers or rain. If we are forecasting showers, we expect the rain to fall on an intermittent basis and from cumulus-type clouds. The showers may vary greatly in intensity over just a few minutes or a few miles. For example, lets say that the forecast for today is calling for a chance of showers. That means that if the rain does develop, it will be on and off, rather scattered, may vary in intensity over just a couple of minutes, and fall from cumulus-type clouds.\n\nIf the forecast for today called for rain, it means we expect the rain to fall rather steadily and from a flat, stratus-type of cloud, and won't change much in intensity from hour to hour. It also means that the rain will fall over a fairly large area, not like showers, which usually fall over smaller areas.
659124
Lots of reasons.  It depends on the air temperature and moisture content, the area that the water evaporates from, local geography (like mountains and lakes) as well as the composition of the cloud (water or ice crystals).
191055
clouds fall all the time, in the form of rain or snow. The cloud is not a container for moisture, it IS the moisture.  \n\nLuckily, it falls gently or heavily, but not all at once!  I think maybe you were asking "what if a cloud fell all at once," in which case I'd say YIKES.  Kind of like a tsunami from the sky, I guess!
836414
We can not control clouds but we can diver the direction of which it passes.  By using bombs and other chemicals it is possible.  It is used where agriculture lands are dried due to lack of rains.
12325
Another individual stated that the clouds act as a blanked and keept the earth warm.  That is an accurate answer. So, let's look a little deeper.\n\nFirst, clouds are the formations of moisture.  The thicker the clouds, the more moisture that is in them. \n\nNext, remember that heat rises.  During the day, the earth is warmed.  It cools at night.  The heat rises into the air.\n\nWater has a high specific heat, meaning a large amount of energy is needed to heat the water.  Likewise, it take a long period of time to cool the water.\n\nAs the clouds cover the earth, they are insulating the land.  Thus when the heat rises, it hits the clouds creating a barrier.  Thus the rate of cooling is slower than when there is not any cloud cover.\n\nPlease note there are exceptions to the rule.  We've all seen or heard of snowstorms coming in and the air is cooling very quickly.  But the general rule is that on a cloudy winter night, the temperature will not drop as low as if there were no clouds.  And you are less likely to scrape frost from your windshield.
560715
If you mean on the surface, then yes. There is a big misconception about this.\n\nIt needs to be 100% relative humidity where clouds are developing NOT on the surface.\n\nThe dew point is the temperature at which saturation occurs (100% humidity). When the dew point is reached at cloud condensation level, then clouds will form & precipitation may occur.\n\nHumidity is measured in several different ways. Relative humidity is how much water vapor compared to how much it could hold at a certain temperature. This is the one we use most often.
1066996
Because the Rain King is watching you more closely than Santa Claus. He is up there on cloud #519 with his telescope and xray goggles. When he sees you are off of work, he says "hahahaha now it's the time to make some rain. Bwaahahhahahahaa". Then he laughs like a mad scientist maniac.
1112416
Water molecules in the air are continually shifting from liquid to vapor. As the Brownian motion and swirling air currents or breezes are moving them around. \n   Thus some of the water at 100 % humidity will be condensing on cooler surfaces while others are evaporating from warmer surfaces eg. your skin.\n   P.S. Your question didn't say but I hope you are standing under a umbrella or something cause at 100% humidity it's likely to be raining. \n\n  Also humidity is relative to air temperature so if the sun is shining during this sun shower, the true quantity of vapor in the air may continue to rise, while humidity actually falls.\n  Nature is truly a conundrum, and even the best super computers, and weather models fail to predict what the weather will do.\n So don't strain your brain.
655206
This has to do w/ the way it forms in clouds.\n\nAs warm moist air rises, it will expand & cool. When it reaches the dew point, it will condense on particulates in the air such as pollen, dust, salts, pollution, etc. This is the formation of a cloud.\n\nThe condensation nuclei described above is the primary source for the shape of the raindrop that may eventually form from the cloud.\n\nAs the water droplets bump into each other, they will begin to stick, growing larger & larger.\n\nWhen wind currents can no longer hold up the droplets, gravity wins the tug-of-war & the droplet will fall.\n\nSome people mistakenly believe that raindrops are "teardrop" shaped. This is not true. They are spherical as they fall through the atmosphere. That is until they hit something.
701886
because the rain god rides on a plane that follows a train that cannot cross a moraine...\n\nand where ever that train goes that plane follows with the rain god, bringing the rain.
12957
It depends on what time scale you are asking.  Ever, being ever in the earths history?  I would think that it has rained at some point everywhere.  Or, rain being the liquid form of water.  If that being the case, it has probably never rained at the north and south polar regions.  It is too cold, and snows.