Thread: Explain rain... How is it possible ?

Yes I know it rains..and I do understand the condensate nature of clouds.

That changes in pressure and temperature force the condensate to fall to Earth's surface. Rain.

But I ask this question because a close friend whom lives in 'Dubai' rang me because it was raining..

He tells me it has not done this for Two Years.. and he then asked.. So here it is...

" If water is heaver than air, and it is... How does it not rain before it rains here..." ? Dubai.

I told him that evaporated water is drawn into the atmosphere and carried by air movement to other places..

Only when changes in air pressure, and temperature change the state of the moisture held in the air does it fall as rain..

How would you explain this..? He is a Doctor of medicine.. not so much science and astronomy..

Roll a person in a parachute and they will plummet to the ground from the sky. Let them use the parachute properly, they will gently float down. Same weight, same materials, different results. (Yes, that's a VERY bad analogy for rain, but the main point is: your friend in Dubai may think he is comparing Apples with Apples - but he isn't).

Watch a puddle evaporate in the sun. You don't see droplets of water rising from the ground. Evaporation isn't rain in reverse. Water in the sky, in clouds seen and unseen, isn't in the same concentrations as when rain forms (from "lots" of water molecules getting together - the droplets then get too heavy for the air to hold; and it falls.)

That's the principle behind cloud seeding. A chemical is spayed into clouds, to provide something for the water molecules to start clinging to, and rain is formed.

Originally Posted by Bananas

Evaporation isn't rain in reverse.

Right, water dissolves in air, like sugar dissolves in coffee. The sugar is heavier than the coffee and falls to the bottom, until it dissolves. We're lucky that carbon dioxide dissolves in nitrogen and oxygen, because it's heavier than they are--if CO₂ fell to the bottom of the atmosphere, we'd be suffocated.

Like salt dissolves in water, and sometimes precipitates out. Water dissolves in air, and sometimes ... precipitates out.

Originally Posted by grapes

Like salt dissolves in water, and sometimes precipitates out. Water dissolves in air, and sometimes ... precipitates out.

Thats a wonderful explanation. If I fall back on my career and end up being a teacher I'm stealing that Grapes.

Where do you think I got it from?

There's a reason they call it precipitation!

Precipitating persistently.. is what it's doing here.. but Nigel in 'Dubia' can not remember rain like they are seeing..

so much water in such a short time.. He can not understand how so much water can be aloft at all..

I told him our atmosphere is like a sponge.. It caries a lot of water.. Its called humidity.

If it reaches or exceeds boundaries of suspension it begins to condensate and falls Earthward. Its called 'rain'..

If warm moist air is cooled it can change the ability to carry water.. snow, hail and driving rain storms are natural events of Earths atmosphere..

Please feel free to contribute your answers to this... I will be sending him your replies..

Your friend is a doctor of medicine and doesn't understand the processes behind rain? Does this concern anyone else?

the atmosphere is about what, 78% nitrogen gas (N2- molecular weight 28 point blah blah)- 20% oxygen (O2 - molecular weight 32 point blah blah) and 2% argon and hydrogen (hydrogen present in water vapor)? - I'm doming all that but its accurate enough.

Water (H20) has a molecular weight of 18, which is less than O2 gas and N2 gas- but is held together in liquid form due to hydrogen bonding effects - unique bonding properties between Hydrogen and either oxygen, nitrogen, and I BELIEVE Fluorine. When enough energy is present the (l) water becomes (g) water.

As it rises in the atmosphere it loses energy and hydrogen bonding condenses enough of the (g) water for gravity to take hold of and returns it to earth as (l) water. Since this doesn't happen instantly, the (g) water seldom falls on the same spot rose from. And harder rains are due to more energy converting a larger mass of (l) water to (g) water.

(l) = liquid
(g)= gas

I'm sure everyone could infer that though.

Originally Posted by JFalz1024

(l) = liquid
(g)= gas

I'm sure everyone could infer that though.

Almost...

Yes a 47 year old Doctor of medicine does not understand water as a gas..

He said "It's 'steam' like as in fog. Water can not be a gas..."

and I have tried to put it right... He does not have time for 'this' .. I said he should find some.

You are wrong.. Best you do some research.. and 'find' some time. and I tried to relate..

That water on Planet Earth does have all three states.. As a GAS, as a liquid as in water and steam..

Which are not the gas but just droplets..of liquid.. and of coarse of ICE.. as in hail and ground ice, sea ice..

'Yes' .. I too want for a explanation of how you get to 47 and being a Md of medicine

working with the knowledge of the drugs and body functions..

Yet, not have grasped that 'weather' is a complex subject that might require some thought and attention if you ever want for a understanding..

and thanks to you JFalz 1024.. you have helped..