Why don't the clouds fall down?

Question

Although it may not seem like one, this is actually a serious question. Clouds appear to have more mass than thin air, so why do they not fall down? (Leaving fog out of the equation, it is just a temporary phenomenon)

Answer 1

Grace posted a good answer, but only the last couple paragraphs are particularly relevant to the question.

Clouds are not static but dynamic - many things happening. Clouds form when rising air becomes saturated and the water vapor condenses to form tiny droplets or crystals. Because there is rising air in a cloud (though some areas where it sinks also - flying thru a large cumulus cloud often reveals small clear areas inside), the upwad motion can easily suspend droplets - some updrafts are strong enough to suspend hailstones. Yet all things being equal, the tiny droplets do fall very slowly to earth - would take hours if there no vertical air motion was involved and they somehow did not evaporate in unsaturated air below cloud base - which typically happens quickly to any which do. I have seen the bases of clouds sink because of downdrafts with raindrops which are evaporating (thus causing the air to remain saturated below the original cloud base) - but that happens much quicker than it would with no downdraft contributuing. Cloud droplets by themselves would cause a cloud base to sink imperceptibly slowly - which probably does happen in some cases.

Few processes in the atmosphere are simple, so neither can a good explanation of them be.

Look at cirrus clouds that are wispy and rise/curl up toward the end - some altostratus do this also. The higher end is always in the direction the wind is blowing to. That should tell you what you need to know about vertical motion in areas where clouds form, and what tends to happen to the tiny droplets and crystals in them.

Answer 2

I remember my old and intelectual Grandpa telling me about clouds...

As you know, clouds are full of evaporated voter... The ones that are darker are containing more mass of water. Therefore, they'll be lower and closer to the earth... the light, white clouds on the other hand are containing less mass and are higher and fluffier than those that are on the bottom ready to hail over our heads.

Well, that's what my Grandpa taught me... but I have a feeling that clouds DO fall down. I get that idea from fogs... fogs are the same evaporated mass of water aren't they? Whenever it's foggy, you'd see cars being all wet, right? But I'm not a scientist, nor a meteoralagist. I just gave my opinion and I hope I answered your question.

Answer 3

A cloud is a visible mass of condensed droplets or ice crystals suspended in the atmosphere above the surface of the Earth or another planetary body. The branch of meteorology in which clouds are studied is nephology.

On Earth, the condensing substance is water vapor, which forms small droplets of water (typically 0.01 mm of ice crystals) that, when surrounded with billions of other droplets or crystals, are visible as clouds. Dense deep clouds exhibit a high reflectance (70 to 95%) throughout the visible range of wavelengths: they thus appear white, at least from the top. Cloud droplets tend to scatter light very efficiently, so that the intensity of the solar radiation decreases with depth into the cloud, hence the grey or even sometimes dark appearance of the clouds at their base. Thin clouds may appear to have acquired the color of their environment or background, and clouds illuminated by non-white light, such as during sunrise or sunset, may be colored accordingly. In the near-infrared range, however, clouds would appear very dark because the water that constitutes the cloud droplets strongly absorb solar radiation at these wavelengths.

Clouds form when the invisible water vapor in the air condenses into visible water droplets or ice crystals. This can happen in three ways:

1. The air is cooled below its saturation point. This happens when the air comes in contact with a cold surface or a surface that is cooling by radiation, or the air is cooled by adiabatic expansion (rising). This can happen:

along warm and cold fronts (frontal lift)
where air flows up the side of a mountain and cools as it rises higher into the atmosphere (orographic lift)
by the convection caused by the warming of a surface by insolation (diurnal heating)
when warm air blows over a colder surface such as a cool body of water.
2. Clouds can be formed when two air masses below saturation point mix. Examples are breath on a cold day, aircraft contrails and Arctic sea smoke.

3. The air stays the same temperature but absorbs more water vapor into it until it reaches saturation.

The water in a typical cloud can have a mass of up to several million tonnes. However, the volume of a cloud is correspondingly high, and the net density of the relatively warm air holding the droplets is low enough that air currents below and within the cloud are capable of keeping it suspended. As well, conditions inside a cloud are not static: water droplets are constantly forming and re-evaporating. A typical cloud droplet has a radius on the order of 1 x 10 -5 m and a terminal velocity of about 1-2 cm/s. This give these droplets plenty of time to re-evaporate as they fall into the warmer air beneath the cloud.

In words you'll understand it means that the clouds are water vapor, and when the vapor builds up enough it rains, so in a sense the clouds fall down when it rains

Answer 4

Clouds appear becuase of a delicate balance between pressure, temperature, and the concentration on water in the atmosphere. This most commonly occurs higher up in the air. However, clouds often do fall closer to the earth. Have you ever seen a skyscraper that is obscured by clouds? Clouds can appear just about anywhere, they just happen to be most common in the middle atmosphere.

Answer 5

Individual droplets of water in a cloud do fall down although very slowly. The bottom of a cloud is the point at which these droplets evaporate. If the cloud is dense enough then these droplets merge together and become big enough to fall rapidly and they drop out of the bottom of the cloud as rain.
A good question.

Answer 6

Think about density, if you say clouds appear to have more mass than air it doesn't mean clouds actually have more mass than air by volume.

Never thought of it seriously but it's a interesting question after all.

Answer 7

sometimes they do. its called rain. and fog is just a cloud that has "fallen down" actually it has to do with the "dew point" look it up.

when the water in the air (humidity) and the temperature are near the point where water changes physical state from gas to liquid, you get a cloud.

but the sun is heating most clouds from above, just as cooler air is cooling clouds from below or from one side of an atmospheric front.

Answer 8

The same reason the clear air below them does not fall up.

In reality clouds and clear air do move up and down all the time - ever seen fog!!!

Answer 9

clouds do fall down its called fog i hope that has answered you question without being sarcastic

Answer 10

they are in the atmosphere. where the air is thinner and they are just like gathered steam (they are water) I don't have a real answer. But interesting question.