Why does moist air at higher elevations produce clouds and rain?
474726
You have gravity holding down air at lower elevations due to the mass of the Earth. The higher you rise, the less gas there is contained in the atmosphere (but you probably already know this). As you have less mass and more vacuums in higher altitudes, the need to fill the vacuum becomes much greater. The water starts to fill here and other water tends to coagulate around these base droplets. You eventually find groups of water together that tend to vary based on temperature.
23018
A rain shadow forms on the side of a mountain that doesn't receive much rain. The reason for this is that clouds tend to form over an ocean, where there is a lot of moisture, and then move inland. The heating and cooling patterns where land meets ocean cause moisture laden clouds to move inland. When cloids encounter a mountain range, air flow is pushed upward, the air becomes colder and can't hold as much moisture, and it rains. This is called the orographic effect.\n\nOn the other side of the mountain, clouds have been emptied of most of their moisture, and a "rain shadow" is created, which is an area that receives little rain. This is why deserts form on the leeward side of mountains, meaning the downwind side of the mountain.\n\nIf you look at a map of Southern California, the Mohave Desert is in a rain shadow.
630793
Clouds are formed by water vapor. And high pressure can hold more water vapor. So when vapor moves into a low pressure system it condenses and and forms clouds and those clouds precipitate when the system cant hold no more water vapor
92209
It rains because the upper atmosphere is warmer than the air at the ground. Generally this is freezing rain, but not always.
297833
Clouds are made of water vapor.  You inhale clouds every time you walk into a patch of fog, because fog is just a cloud at ground level.  Clouds are formed when water evaporates from the surface of the Earth and makes its way upward.  The water condenses and we get a cloud.  When clouds get too laden with water, it falls in liquid form and we get rain.
562921
High pressure is hot. If it hits a low pressure area, you get rain.
350316
A reading of 100 percent relative humidity means that the air is totally saturated with water vapor and cannot hold any more, creating the possibility of rain. This doesn't mean that the relative humidity must be 100 percent in order for it to rain -- it must be 100 percent where the clouds are forming, but the relative humidity near the ground could be much less.\n\nHumans are very sensitive to humidity, as the skin relies on the air to get rid of moisture. The process of sweating is your body's attempt to keep cool and maintain its current temperature. If the air is at 100-percent relative humidity, sweat will not evaporate into the air. As a result, we feel much hotter than the actual temperature when the relative humidity is high. If the relative humidity is low, we can feel much cooler than the actual temperature because our sweat evaporates easily, cooling us off.
22072
Clouds aren't just random droplets of water. What they are is tiny droplets of water that have condensed from water vapor in areas where the conditions (temperature, air pressure and humidity) are exactly right. Anywhere where you have the correct combination of these conditions, you'll get a cloud. Anywhere that you don't, you don't.\n\nAreas with this kind of conditions don't occur in random tiny places. Instead, there will be a large area of one condition that gradually shifts into another. (If this doesn't make sense, think of just temperature. You don't get a different temperature at every spot on the globe. Instead, you get a large area of warm air that gradually shifts into a large area of cooler air. The same is true for air pressure and humidity.) This is why you get a large area of 'cloud' in one place and nothing at all in another. You can think of clouds as being physical maps of the weather conditions in the sky.\n\nThis is also what holds the clouds up. In general, if a cloud is high up in the sky, the conditions just below it aren't right for the cloud to form. As the water droplets fall, they reach areas with the wrong temperature or pressure and evaporate again. Only if the clouds become densely packed enough for the water to form large enough droplets can the droplets fall to the ground. Not all clouds form high up, either... sometimes the right conditions can occur at groundlevel, giving us fog.
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A low pressure system occurs in the air above the sea surface. It is where warmer, lighter air is rising. A high pressure system forms where cooler, drier, heavier air is sinking. Winds blow from areas of high pressure towards areas of low pressure.\n\nAs warm moist air over the ocean rises above a low pressure system it cools. Once the water vapour in the air cools to a certain point it condenses to form tiny water droplets which we see as clouds. If there is enough turbulence in a cloud and the cloud is big enough the water droplets clump together until they grow large enough to fall out of the cloud as rain.\n\nIn a strong low pressure system lots of warm moist air is rising rapidly and so very big clouds can form which have a great deal of turbulence inside. These are called storm clouds. Because they hold lots of moisture and because the tiny droplets of water inside collide with each other very frequently, very large raindrops can form which fall to the ground in heavy downpours.
186119
rain comes from clouds. clouds are actually water vapour floating in air. when they become really condensed due to a drop in temperature then they form large drop of water which cant stay afloat and so rain happens.
51376
It depends on a number of variables. One factor is the temperature difference between two air masses. The warm air will hold more water than cold air, so if a warm front hits a very cold air mass the cold air will cool the warm air and it will become oversaturated with water vapor. The more the warm air is cooled the more rain will fall. \n\nAnother factor is the way the air masses are moving. If a warm front moves over cold air slowly it will form a gradual transition with the cold air remaining near the ground and the warm air climbing gradually over it. This will produce a prolonged period of rain. If a cold front pushes under a warm air mass it may form a much steeper boundary area between the two air masses. This can produce very hard short periods of rain. \n\nHere's a little diagram:\nhttp://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0006324.html
1181166
Air is heated by the surface of the Earth on a Hot and sunny Day.  Hot air rises.  AS it rises it expands due to lowered atmospheric pressure.  As it expands it cools and begins to decend again.  Also if the air is moist as it cools it must release the moisture (rain -or hail if it is high and cold enough.)  This begins a circulation pattern up in the middle and down outside.  Often hail will begin to fall only to be caught in an updraft and carried aloft again.  This cycle continues until the hail is too heavy for the updrafts to lift it and it makes it to the ground.  This is why very strong thunderstoms with violent updrafts produce large hail.
577442
The water vapor which is released through the combustion of the gases becomes like fog and converts to water droplets when cooled in the air. This is just like the clouds
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In some countries, they spray the top of the clouds ("seed the clouds") with chemicals (AgI or AgCl).  This causes the small water droplets in the cloud to grow, and finally the drops are big and heavy enough to fall to the ground in the form of rain.\n\nThe reason for doing this could be that you really don't want rain in a certain area, and you think it is a better idea to make the potential rain clouds "release the rain" in another area, before they have moved with the wind to the area you want to protect.\n\nSo, the rain is not really artificial, but the cause of the rain is artificial.
1034117
no clouds are not solid they are made  up of water  vapor and gas. Clouds are formed when air contains as much water vapor (gas) as it can hold. This is called the saturation point, and it can be reached in two ways. First, moisture accumulates until it reaches the maximum amount the volume of air can hold. The other method reduces the temperature of the moisture filled air, which in turn lowers the amount of moisture it can contain. Saturation, therefore, is reached through evaporation and condensation, respectively. When saturation occurs, moisture becomes visible water droplets in the form of fog and clouds.\n\nIt should be noted that condensation by itself does not cause precipitation (rain, snow, sleet, hail). The moisture in clouds must become heavy enough to succumb to gravity and return to earth's surface. This occurs through two processes. In cold clouds ice crystals and water droplets exist side by side. Due to an imbalance of water vapor pressure, the water droplets transfer to the ice crystals. The crystal seventually grow heavy enough to fall to earth. In the second process, water droplets in warm clouds collide and change their electric charge.Droplets of unlike charge attract one another and merge, thereby growing until they have sufficient weight to fall.\n\nThere is no difference between fog and clouds other than altitude. Fog is defined as a visible moisture that begins at a height lower than 50 feet. If the visible moisture begins at or above 50 feet, it is called a cloud. Two common types of fog are called radiation fog and advection fog. Radiation fog forms during the night as the earth's surface cools and the air immediately above it cools in turn by conduction. If the air is moist enough, the cooling causes it to reach saturation and visible water droplets form. We often call this type of fog ground fog because it lies so close to the surface. Advection fog forms when warm moist air moves over a colder surface (advection means to move horizontally). A perfect example is on the west coast of continents. Prevailing westerly winds move moist air from over a warm ocean area to over the colder waters off the coast. Fog forms and is carried by the westerly over the land.\n\nClouds can form anywhere in the troposphere, and although condensed liquid, they are light enough to float in the air and move from place to place by the wind. Clouds are classified according to appearance and height. Based on appearance, there are two major types: Clouds of vertical development, formed by the condensation of rising air; and clouds that are layered, formed by condensation of air without vertical movement. When clouds are classified by height, there are four classes: high, middle, low, and vertical development.\n\nCloud names, of which there are twelve, combine appearance and height. A brief description of the root name will indicate this combination of features.
380819
when clouds melts then it rains,its the water cycle...water evaporates due to heat n goes up n along with dust particles  it forms what we called clouds n these clouds keep floating n when temperature rises n clouds reach certain atm. pressure due to it melting,,raining occurs
404328
For clouds to form the air has to be unstable, meaning that the air at the surface is warmer than the air above. Remember the saying warm air rises? So when the air rises it hits a level called the Lifting Condensation Level or LCL. If the air rises to this point it then can start to condense on particles in the sky forming clouds.