Why does dew form on grass, but not on concrete etc?
482136
concrete conducts more heat from the ground below and prevents dew from condensing on it.
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.
760901
Grinding with sand causes glycogen to precipitate.\n\nhttp://www.jhc.org/cgi/reprint/17/8/527.pdf pg., 5\n\nHope this helps.\nAndy
652652
Actually, no one has quite gotten into the reality.  Rain is almost all rain.  But something like 99% of all precipation drops form around something called condensation nuclei.  Basically that's a fancy term to say some small particle in the air.\nThis can be dust, clay, sea salt, pollutants (leading to smog, acid rain, etc), even tiny insects... whatever's available.  Water actually takes advantage of the particle's curvature, allowing water to condense even though the air isn't 100% saturated.\nCloud seeding is an attempt to induce additional rainfall by adding more particles.  It is only marginally useful in most places.\n\nThere are also small amounts of mixed in gases (nitrogen and oxygen mainly) and any other pollutants the raindrop comes into contact with while falling through the atmosphere.\n\nBut mainly rain is just water.  Awesome stuff, too!\n\nHope I helped,\nGod bless,\nShane
348720
(m)\n\nThe amount of moisture air can retain is determined by its temperature and, to a lesser extent, its pressure. Any sufficient drop in temperature or increase in pressure will cause moisture to condense out of the air. \n\n \n\n Relative humidity is the amount of moisture that is present in the air, compared to the total amount the air could hold at a certain temperature. For example: One cubic foot of air at 80°F, 27°C can hold about 12 grains of moisture.\n\nIf it is holding all 12 grains, it is said to be at 100% relative humidity or saturated. If that same cubic foot of air is holding only 6 grains of moisture, it is at 50% relative humidity.\n  \n Saturation point is the point at which air is holding all the water vapor it can (100% relative humidity). If we added more water vapor to saturated air, the water vapor would condense into a liquid.\n\nRemember that a drop in temperature or increase in pressure will cause moisture to condense out of air that is saturated.\n \n\n  Condensation is the changing of water vapor into a liquid.\n\nDew point is the temperature at which water vapor in the air condenses into a liquid.\n \nPressure dew point is more meaningful because it indicates, at a given pressure, the temperature at which condensate forms in the compressed air lines.
1107206
Hail forms on condensation nuclei such as dust, bugs, or ice crystals, when supercooled water freezes on contact. In clouds containing large numbers of supercooled water droplets, these ice nuclei grow quickly at the expense of the liquid droplets because the saturation vapor pressure over ice is slightly less than the saturation vapor pressure over water. If the hail stones grow large enough, latent heat released by further freezing may melt the outer shell of the hail stone. The growth that follows, usually called wet growth, is more efficient because the liquid outer shell allows the stone to accrete other smaller hail stones in addition to supercooled droplets. Once a hailstone becomes too heavy to be supported by the storm's updraft it falls out of the cloud. The reason rain can't fall, is typically because of the strong winds inside a thunderstorm cloud. These winds hold the rain and freeze it. As the process repeats, the hail grows increasingly larger. When a hail stone is cut in half, a series of concentric rings, like that of an onion, are revealed. From these rings we can determine the total number of times the hail stone had traveled to the top of the storm before falling to the ground.\n\nEven though temperatures at this height are below freezing, most of the cloud's moisture is super cooled. This means it remains liquid because it lacks a surface on which to freeze. As soon as a super cooled droplet collides with potential nuclei—ice crystals, frozen raindrops, dust, or salt it freezes quickly.
311001
It does, tho not necessarily rain that's made of water. It could be acid rain or something like that.
693847
I think that hard frost is known as hoarfrost. Hoar frost is formed when the dew point is warmer than surface but colder than the air temperature, and colder than freezing point.
997634
Dew results when water condenses out of the air as a liquid. Dew is liquid water.\n\nWhite frost resutls when water condenses out of the air direstly as ice crystals. White frost is solid water, AKA ice.\n\nBlack frost results from dew freezing. Unlike white frost black frost exists initially as water and then freezes, wheras white frost never exists in liquid form.
467833
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.
616151
It works by removing the water vapour (like steam) from the air. Water vapour condenses back to a solid for when it meets a cold surface. The water then appears as if from knowhere (as in condensation on a glass or can containing a cold drink) This action takes place when the dew point of the vapourised liquid is reached
664148
What is?\n\nAcid rain" is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry. \n\nWet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depend on many factors, including how acidic the water is, the chemistry and buffering capacity of the soils involved, and the types of fish, trees, and other living things that rely on the water. \n\nDry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. When that happens, the runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone.\n\nPrevailing winds blow the compounds that cause both wet and dry acid deposition across state and national borders, and sometimes over hundreds of miles.\n\nRead:http://www.fs.fed.us/ne/newtown_square/aboutus/history.shtml\n\nhttp://www.nautilus.org/archives/fora/energy/9704A_VonHippel.html\n\nee this Epa report:http://www.epa.gov/airmarkets/cmprpt/arp03/summary.html
30608
Clouds are formed when warm moisture laden air is forced upwards either by a physical obstruction such as a hill/mountain or by being heated by the ground/sun.\nAs it rises it cools, and cold air can hold less moisture than warm air, so the vapour condenses out into droplets that form our clouds.\n\nFog is caused when moisture laden air is cooled by contact with the ground or water, it gets colder and colder until any moisture condenses out.  Fog forms as a layer as the air above it tends to be warmer due to rflected heat from the sun and also becauseof the lack of wind to stir the two layers together.  This is often referred to as an inversion.
585225
The chemistry is in the changes in the state of matter & water's properties such as cohesion & adhesion.\n\nWater is evaporated from the earth's surface, rises with warm air masses, cools & condenses on condensation nuclei w/in the upper atmosphere (property of adhesion). Clouds form & continue to build as long as there is updraft (warm rising moist air).\n\nBecause of water's property of cohesion, the tiny water droplets will begin sticking together. When they become too heavy to w/stand the pull of gravity, they will descend & fall as rain.
448207
Since warm air rises and cold air sinks, when the sun comes up the warmth causes the cold air with it's frozen particles to sink, therefore landing on top of the grass. This "frost" will only last till the suns rays cause them to melt. Remember, it's still cold at ground level while the sun begins to feel warm to us.
3829
It is more difficult for the moisture to accumulate on your windshield when it is windy.  It takes some time for water to freeze when there is no wind at all so you can imagine how difficult it would be for water to accumulate and freeze when the wind is blowing.
210582
Hygroscopic materials don't necessarily attract moisture from the air, but they do trap it. Each material is different, but typically the smaller water molecules become lodged in larger pores or crevices between the larger material's molecules.\n\nA good place to start is Wikipedia.