How Much Does A Cloud Weigh?

MyNameIsFred writes "ABC News is running an article revealing unexpected facts about weather formations. Ever wonder how much a cloud weighs? What about a hurricane? A meteorologist has done some estimates and the results might surprise you..." Reports that include the phrase "more than all the elephants on the planet" are always welcome.

Comments

sad

[mse61]

It isn't saying much when you have to relate the measurement of weight to an elephant so the populous that reads it can grasp the magnitude of the number. In fact I find that rather pathetic...

Target Audience?

[i_am_nitrogen]

Who on earth is this written for? It says at the bottom that at least two people contributed to the report. The language is like that of a 4th grader. Is this what all ABC News reports look and/or sound like?

This makes the BBC seem like something written by Stephen Hawking.

Re:Target Audience?

[Tokerat]

...perhaps that's so it may be used in a 4th grade science class? Honestly, I don't think this is exactly hard-hitting journalism targeted at America's most prominent adult citizens...

It's just a neat little factoid little Billy can print and bring to teacher for extra credit. Also, an interesting fact, if it's something you never considered before.

This surprises you?

[rblancarte]

We are talking water. Water is very heavy. It is just that water in a cloud is in vapor form, and also floating in the sky that we sort of forget that it is still water.

And to be honest, the numbers (200,000 elephants in a storm cloud) don't shock me. Think of the destruction caused by floods, which are caused by rain. In some ways, it makes sense.

Re:This surprises you?

[rew]

Water in a cloud is no longer in vapor form. The water in the air below the cloud is generally in vapor form. It's transparent, as opposed to whitish when it's in small particles.

The weight of the water in a unit of volume of air just below your standard cumulus cloud is about the same as the weight of the water-vapor in the could.

Anyway, your standard cloud being 1km x 1km x 200m, the weight of the AIR in that cloud comes to 1.2 kg/m^3 * 1000*1000*200 / 1000 kg/tonne= 240 thousand tonnes. That should be about 20 times as much as the weight of the water in the cloud. (there is about 5% water in air/cloud).

I made a hot-air baloon of about 64 m^3 once (over 60 kg, about the same weight as a human!). Once it was rising, it was impossible to stop using the line we used: 6kg strength. Once it was moving at 1m/s it should have taken at least 10 seconds to slow it down. If you try to hurry it a bit, SNAP. That's what happened. The baloon was not weighted at the bottom, so it turned over, let most of the hot air escape, and crashed 3km further in some cactusses.

I find your sense of superiority pathetic.

[Chuck Chunder]

I see no reason why most people should have some natural appreciation of what "550 tons" actually means.

Re:NEWS ALERT (Summary)

[digitalunity]

That's why I never listen to the news.

The sky isn't blue at all. Sunlight shining through our atmosphere makes it appear blue. Evidence of this is any sunset; then it isn't blue at all.

Re:NEWS ALERT (Summary)

[TummyX]

Grass isn't green. Sunlight reflecting off it makes it appear green. Evidence of this is at nighttime; the it isn't green at all.

Re:NEWS ALERT (Summary)

[digitalunity]

The word 'Sky' is an Old Norse word. It mean's cloud. It came into the common english language around the year 1100. You are absolutely correct that they aren't synonymous. 'Sky' is usually referring to our atmosphere from the vantage point of earth, but in either case, it is referring to the same thing.

Re:NEWS ALERT (Summary)

[Idarubicin]

The sky is composed of nitrogen and oxygen in large proportions. Both are transparent materials in gaseous form. They do, however, refract light like a prism.

They do indeed--but that has precious little to do with why the sky is (usually) blue. Refraction occurs when light passes from a medium with one refractive index into another, and bends in so doing. There are lots of websites on the topic. The amount of bending that occurs depends on the material and on the wavelength of the light. Typically, materials have a higher index of refraction for shorter wavelengths--this dependence of refractive index enables prisms to separate light into component colours.

The apparent colour of the sky depends not on refraction (air has an index of 1.003, only a shade more than vacuum's 1.000) so light bends very little passing through the atmosphere. The important effect is Rayleigh scattering. Light with shorter wavelengths is scattered much more strongly--red and yellow light from the sun follows a fairly direct path to the viewer, so the sun appears as a yellow disc. Blue light is scattered repeatedly by the atmosphere, resulting in a diffusely blue sky. Interestingly, if you take a long exposure photograph on a moonlit night, the sky will still show up as blue from scattered moonlight.

Incidentally, I would call the 'sky' blue, even though the gases of the atmosphere are (except around cities) colourless. That's the colour you see when you look up, in the direction of what a layperson would call the sky. Oh, and I am a physicist.

If you look at a blue ball through the edge of a prism and it looks red, is the ball still blue? I think so.

If you look at a 'blue' ball through the edge of a prism, it will look blue or black--if it reflected large amounts of red light, then it wouldn't appear blue without the prism in the first place.

I would call you a pedant, if you were right.

I would still call you a pedant--and a condescending one, at that--even though you're a little iffy on scattering of light. If you would like some further pedantry, I would be pleased to explain why the sky is red at sunset.

Re:NEWS ALERT (Summary)

[UTPinky]

"Grass is still green, right?"

Only on the other side.