Why is it that cloudsseem so large, yet water vapor makes only 4% of the atmosphere?
86622
The first point you need to realise is that clouds are NOT water vapour. They are liquid water. It wouldn't matter how large clouds were or how many there were they wouldn't have any effect on the amount of water vapur in the atmopshre.
4645
because of water vapor (in the air...gives it a blueish hue.  not much to due with physics... maybe chemistry.
854216
Since a cloud is made up of lots of small droplets of condensed water (or, in the case of some clouds, the condensed water freezes into ice crystals), if you were able to "shake" the cloud (get the water droplets moving around randomly) they would collide and form larger water drops.  These drops should then eventually become heavy enough to drop from the sky as rain.\n\nWikipedia has a pretty good article on clouds.
195502
I did a Yahoo Search for:\nflat cloud bottom\nhttp://search.yahoo.com/search?ei=utf-8&fr=slv1-&p=flat%20cloud%20bottom\n\nand I found this page which is from a sight call "Ask A Scientist" where they answer this very question:\nhttp://www.newton.dep.anl.gov/askasci/wea00/wea00041.htm\n\nThe answers aren't great, but it seems to do with level at which water vapor begins to condense into cloud forming water droplets.  It depends on the temperature or air pressure.  The reason the bottoms of some clouds look flat is that these conditions are pretty uniform over a large area.  As you go higher up, temperature and pressure decrease and the transition point is a fairly consistent altitude for that moment in time.\n\nFor more information on clouds and cloud types:\nhttp://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml
543373
We have air around us. The atmosphere has high preasure and low preasure. When the high preasure area turns into low preasure, the air moves from high preasure area towards the low preasure. This movement of air from one area to another causes the wind. \n\nIt has nothing to do with clouds. The faster the low preasure area is formed, depends on whether you have clouds, or thunderstorms. Low preasure areas causes rain. This is why normally you have winds before the rain.
195191
Fog is made when water vapor condenses, the same as clouds.\n\nTechnically they are the same thing. Fog is obviously at lower altitudes.\n\nClouds form when warm moist air rises, cools (reaches dew point), & condenses on small particulates (aerosols) in the atmosphere.\n\nFog can form in many different ways. There are about 5 or 6 that I know of...\n\nRadiation: forms on cool clear nights\nSteam fog:forms over water when the water is still warm but the air is cool (think fall nights)\nAdvection: moist air flowing over cool water or land (think San Francisco)\nvalley fog\nprecipitation fog\n\nknow less about the last 3.\n\n:)
835700
Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles (typically 0.0002 mm, or 1/100 th the size of a cloud droplet [1]) about which cloud droplets coalesce. Water requires a non-gaseous surface to make the transition from a vapour to a liquid. In the atmosphere, this surface presents itself as tiny solid or liquid particles called CCNs. When no CCNs are present, water vapour can be supercooled below 0 °C (32 °F) before droplets spontaneously form (this is the basis of the cloud chamber for detecting subatomic particles). In above freezing temperatures the air would have to be supersaturated to around 400% before the droplets could form.\n\nThe concept of cloud condensation nuclei has led to the idea of cloud seeding, that tries to encourage rainfall by seeding the air with condensation nuclei appropriately.
765885
I have no idea what you are asking.  Argon is 0.934% of the atmosphere.  Is that what you wanted?
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
56788
I can answer half of this question, I think. Clouds are water (H2O) in vapor (gaseous) form. Water floating in a classroom? Its still H2O but you'll need to get either a plumber or an HVAC technician to answer that!
1032861
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.
492491
Water vapor is transparent (for most purposes) and so mere humidity in the atmosphere can't be a cloud. Since clouds don't have motors keeping them in the air, and yet stay there for hours in some cases, they can't be solid, for if they were, they'd fall out of the sky and we'd find cloud bits laying around on the ground. And the same is true for liquid as well. \n\nSo what's a cloud? Mostly, it's very small bits, so small that air currents can keep them in the air. The bits can be solid (eg, ice crystals of which snowflakes are examples), or liquid (eg, little drops of water, of which rain is an example). In either case, enough of these small things begin to look white as light passes thorough them and is reflected and refracted and generally diverted. Kind of like the effect of fine particulate suspensions in water. They are sometimes referred to as milky looking. Indeed, milk is white for a similar reason.\n\nThese are usually formed around dust bits, for real. High humidity (forced by cooling temperatures) produces supercooling (ie, ready to condense, if a trigger can be found). The dust motes provides the trigger. With updraft winds, a condensed drop can grow pretty large. And if it goes high enough, and gets cold enough, the drop can freeze (and thus make hail). If the orignal condensation is sufficiently cold, then water will be added to an ice crystal. With the proper history, such crystals become snowflakes.
318431
Atmosphere has a very low heat capacity compared to hydrosphere. It will react strongly on short term (well below diurnal) changes, like insolation (amount of energy absorbed by the sun).
1183383
The sky is beautiful, but clouds are just water vapors. How does a tree grow? Photosynthesis. Knowing how something occurs does make it less beautiful does it?
620707
As air gets warmer it's able to contain more water vapor.  An easy way to illustrate this is in a steamy kitchen or bathroom where you'll see that condensation forms on the coldest surfaces such as windows, mirrors, tiles etc.\n\nWhen the amount of water vapor in the air reaches it's maximum point the air is described as being saturated (saturation vapor pressure or SVP for short).  SVP is therefore reached more quickly when the air is cooler.\n\nWhen air reaches SVP it has to deposit the excess moisture which it does as dew or condensation and the point at which this occurs is called the dew point.  The colder the temperature the lower the dew point which helps explains the cool mornings when there's dew on the grass.\n\nHumidity is a measure of the amount of water vapor that's present in the air and is measured as a percentage of the maximum possible.  So a Relative Humidity (or RH) or say 60%, means that the air contains 60% of the maximum possible water vapor.  As mentioned, the amount of water vapor possible increases with temperature and so RH is affected by temperature.  An RH of 80% in a hot tropical climate is going to feel much damper and humid than an RH of 80% in a cooler climate.
370942
the atmosphere is contains about 380ppm CO2 (.038%) which is up from about 280ppm (.028%) which is what is is estimated at 100 year ago. Water is still by far the majority green house gas though.
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.