[Petrochemicals (OP)]

Even though recently released findings suggest that a temperature increace of 1.5 degrees will lead to a hot house greenhouse effect on earth, the actual effect of water vapour as a proportion is difficult to find information on. Water vapour obviusly precipitates out, where as co2 does not.

https://www.independent.co.uk/environment/hothouse-earth-climate-change-global-warming-greenhouse-gas-sea-level-arctic-ice-a8481086.html

Given that farmers are effectivley creating huge evaporation areas for river water, how much of an extra push is this giving global temperatures ?

https://www.theguardian.com/australia-news/2019/jan/31/photos-reveal-queensland-cotton-farms-full-of-water-while-darling-river-runs-dry

[Bored chemist]

"How much effect does water vapour have as a proportion of global warming ?"
Much the same as it always has.
Unlike CO2 which  we have increased by a third since preindustrial times.

[alancalverd]

There is no doubt that water is the principal determinant of atmospheric temperature, global albedo, mean surface temperature, weather, climate and everything else including probably the genesis of life on earth through the formation of complex molecules in thunderstorms. It covers 75% of the planet surface as liquid and controls most of the remaining 25% as surface moisture, 80% of plant material, or ice. It has a higher specific heat capacity than any other common material, enormous latent heats of melting and evaporation, and is the only substance that exists in all three states (solid, liquid and gas) in nature, including all three simultaneously in the atmosphere.

Unlike every other greenhouse gas, it is inherently destabilising: a higher water content increases the infrared absorption of air, which raises the temperature and allows more water to evaporate. It is also inherently limiting: saturated air at high altitude forms clouds that reflect sunlight and prevent surface heating (or cooling). 

The problem is that we cannot control it, we have no historic data for its distribution, and no adequate model for its global behavior, since even the simplest assumption of a static, homogeneous atmosphere over a smooth ball breaks down as soon as you add planetary rotation and uneven solar heating, never mind surface differentiation between rock, vegetation, water and ice.  The only gross statement we can make is that the mean surface temperature of the planet is inherently chaotic and bounded, and the historic record shows this to be the case.

Fortunately, as water has a lower molecular weight than oxygen, nitrogen or carbon dioxide, it is gradually being lost from the atmosphere so eventually the planet will dry out and we will be left with a more predictable climate like Mars, whose surface temperature is determined by atmospheric carbon dioxide.

Pretty well every human activity, from breathing to farming, increases the rate of evaporation of water, and nothing reduces it. However we do not have an adequate model to predict whether this will significantly increase or decrease atmospheric stability or mean surface temperature over the short (100 - 1000 year) term. What we do know, from the discovery of  plant and animal remains under retreating glaciers, is that the planet has been quite a bit warmer during recorded history when CO2 levels were 30% lower. And what we can predict from recent observations, is that the present distribution of human beings over the planet is not sustainable.

[Bored chemist]

Water in the atmosphere is more complex than the other components for two reasons- the large energy changes needed to melt or evaporate it, and the fact that clouds reflect heat and light (inbound and outbound).

Increased reflection by clouds can act as a negative feedback (i.e. stabilising) mechanism.
But it's not one we can rely on much.

[jeffreyH]

Civilization is pretty much toast at this point.

[Petrochemicals (OP)]

Water in the atmosphere is more complex than the other components for two reasons- the large energy changes needed to melt or evaporate it, and the fact that clouds reflect heat and light (inbound and outbound).

Increased reflection by clouds can act as a negative feedback (i.e. stabilising) mechanism.
But it's not one we can rely on much.

Clouds are not water vapour, whilst they reflect visible light, it is the vapourous water which traps infra red.

Alot more water is evaporated and more energy captured from the sun. Imagine last year, the ammount of extra water that did not reach the sea, but was put onto the land for evapouration. I know it falls out of the sky but we have evapourat3d more water today i should think than we consume in oil all year. (This is a guess, if we do about 20 miles a day, thats 180 gallons per person a year, bit on electric, lots on house heating, say 500 gallons a year per 2 people, 250x60 1500, 000, 000 gallons equivelant a year in the uk or 6 trillion litres) if the farmers industry etc evapourate that much per day its alot of extra.

[Petrochemicals (OP)]

Water in the atmosphere is more complex than the other components for two reasons- the large energy changes needed to melt or evaporate it, and the fact that clouds reflect heat and light (inbound and outbound).

Increased reflection by clouds can act as a negative feedback (i.e. stabilising) mechanism.
But it's not one we can rely on much.

Strangley enough humidity or relative humidity has the greatest effect on water evapouration. Water has to have enough energy to become gas in line with the gas laws.

A windy day means that the airs relative humidity due to it being moving air is lower.
A hot day means the moisture gets to a higher temperature, it also heats the air via convection thus lowering the humidity.

Extra heat from houses means the air is hotter. Extra heat comes from exausts and cooling towers, this rises as water liquid to a high enough altitude and low enough humidity for it to turn into vapour.

Bare earth is an ideal medium for evapouration.

[Bored chemist]

Clouds are not water vapour,

Nobody said they were, but unless you think clouds form because birds carry bits of cotton wool up into the sky or something...

it is the vapourous water which traps infra red.

Clouds do too.
That's why it gets colder quicker on clear nights.

Alot

That's still not a word.

Alot more water is evaporated and more energy captured from the sun.

More than what?
What would  have happened to that energy if it hadn't been used to evaporate water?

A windy day means that the airs relative humidity due to it being moving air is lower.

Humidity is not dependent on wind speed.

Bare earth is an ideal medium for evapouration.

Extra heat comes from exausts and cooling towers

Why don't they use bare earth for cooling towers then?

[Petrochemicals (OP)]

Clouds are not water vapour,

Nobody said they were, but unless you think clouds form because birds carry bits of cotton wool up into the sky or something...

Facetious.

it is the vapourous water which traps infra red.

Clouds do too.
That's why it gets colder quicker on clear nights.

I thought that was to do with convection ? I believed clouds where only good wiih longwave infra red ?

Alot

That's still not a word.

Alot more water is evaporated and more energy captured from the sun.

More than what?
What would  have happened to that energy if it hadn't been used to evaporate water?

Alot should be. Bare earth is a good reflector of solar energy, when wet this energy is absorbed and evapouration commences.dark wet earth light dry earth ?

A windy day means that the airs relative humidity due to it being moving air is lower.

Humidity is not dependent on wind speed.

Movement gives the air more energy thus must increace the dew point

Bare earth is an ideal medium for evapouration.

Extra heat comes from exausts and cooling towers

Why don't they use bare earth for cooling towers then?

Pedant facetious rubbish

[alancalverd]

Some recollections from the glider pilots' meterorology exam:

Night cooling depends primarily on radiation rather than convection.

Bare dry earth heats and cools more rapidly than wet or vegetated earth, due to its lower specific heat capacity.

Whilst turbulent motion increases evaporation (up to the dewpoint), laminar moving air is just air, moving - its dewpoint is unaffected by group velocity.

[Petrochemicals (OP)]

Some recollections from the glider pilots' meterorology exam:

Night cooling depends primarily on radiation rather than convection.

Bare dry earth heats and cools more rapidly than wet or vegetated earth, due to its lower specific heat capacity.

Whilst turbulent motion increases evaporation (up to the dewpoint), laminar moving air is just air, moving - its dewpoint is unaffected by group velocity.

I was thinking more along venturi principle

https://sciencing.com/humidity-wind-speed-affect-evaporation-12017079.html

Yes wet earth will warm less rapidly due to evapourative cooling

Point take about cloud(therefore liquid water particles ) absorsion and emission of shortwave Infrared.

[alancalverd]

Not just evaporative cooling. It takes about 5 times as much heat to warm a kilogram of water through 1 degree than to warm  a kilo of rock through the same interval.

It is true that surface wind increases the rate of evaporation, but only if the air is not already saturated. Motion does not affect dewpoint.

[Petrochemicals (OP)]

Not just evaporative cooling. It takes about 5 times as much heat to warm a kilogram of water through 1 degree than to warm  a kilo of rock through the same interval.

It is true that surface wind increases the rate of evaporation, but only if the air is not already saturated. Motion does not affect dewpoint.

It lowers the pressure, thus decreacing the humidity and therefore the dewpoint is increaced.

I like the fact that the water that the farmers are spraying everywhere increaces the energy absorbed by  500 percent. Alot more mousture waiting to vapourise when the oppourtunity comes along.

[Bored chemist]

I believed clouds where only good wiih longwave infra red ?

Then you didn't notice what colour they are, or you didn't think it through.

[Bored chemist]

It lowers the pressure, thus decreacing the humidity and therefore the dewpoint is increaced.

Two things.
You are muddling cause and effect.
Changes in pressure drive the wind, not the other way round.
Also the changes are relatively small.
A change in pressure from one day to the next of 5% is quite big.
To change the saturation vapour pressure of water vapour by 5% takes a change of less than 1 C (near 20C)

So typical temperature variations during a day give much bigger changes in humidity than barometric pressure changes do, and the pressure changes from the bernoulli effect are even smaller.

So your claim is more or less wrong.

Pedant facetious rubbish

No.
Pointing out that you contradicted yourself isn't pedantry.

Movement gives the air more energy thus must increace the dew point

Two problems.
Dew point depends on the percentage of water in the air, not energy.
So you are wrong.
Also, there are two major ways in which air carries heat, one is motion, the other is temperature.
On a microscopic scale the temperature is also due to motion- molecules typically travel at about the speed of sound.
So it's clear that wind speeds have a small to negligible effect on the energy in the air.
And that's before you remember that one driver of wind is temperature change.
The reason the air is moving is that it already lost heat.

Alot should be.

Not really.

Facetious.

No
Pointing out that you are wrong isn't acting facetiously.

[Petrochemicals (OP)]

I believed clouds where only good wiih longwave infra red ?

Then you didn't notice what colour they are, or you didn't think it through.

I cant see infra red of any wavelength comma Your a dick !

[Petrochemicals (OP)]

It lowers the pressure, thus decreacing the humidity and therefore the dewpoint is increaced.

Two things.
You are muddling cause and effect.
Changes in pressure drive the wind, not the other way round.
Also the changes are relatively small.
A change in pressure from one day to the next of 5% is quite big.
To change the saturation vapour pressure of water vapour by 5% takes a change of less than 1 C (near 20C)

So typical temperature variations during a day give much bigger changes in humidity than barometric pressure changes do, and the pressure changes from the bernoulli effect are even smaller.

So your claim is more or less wrong.

Pedant facetious rubbish

No.
Pointing out that you contradicted yourself isn't pedantry.

Movement gives the air more energy thus must increace the dew point

Two problems.
Dew point depends on the percentage of water in the air, not energy.
So you are wrong.
Also, there are two major ways in which air carries heat, one is motion, the other is temperature.
On a microscopic scale the temperature is also due to motion- molecules typically travel at about the speed of sound.
So it's clear that wind speeds have a small to negligible effect on the energy in the air.
And that's before you remember that one driver of wind is temperature change.
The reason the air is moving is that it already lost heat.

Alot should be.

Not really.

Facetious.

No
Pointing out that you are wrong isn't acting facetiously.

No


No


Im  right



Im right.




Your a dick




(Back on the ignore list till you learn to read)

[Bored chemist]

I believed clouds where only good wiih longwave infra red ?

Then you didn't notice what colour they are, or you didn't think it through.

I cant see infra red of any wavelength comma Your a dick !

Can you see clouds?
I kind of assume you can.
So you know they reflect visible light so you know that they don't just reflect long wave IR so this 

I believed clouds where only good wiih longwave infra red ?

is daft because you know they are also good for reflection of visible light, rather than only being good with long wave IR.

While you are looking at the sky, you may like to pay attention to the colour of the bit between the clouds which shows that, if anything, long wave radiation is scattered less well (all other things being equal) and, in this case, the reflection is due to back-scatter.

So, you are wrong again.
Why not stop- as you put it- being a dick?

[Bored chemist]

(Back on the ignore list till you learn to read)

You may want to revise your view of where the learning deficit lies.

[Bored chemist]

Your a dick !

*You're*