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Evapotranspiration

Lord of Planar

Lord of Planar

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Most of you probably remember me speaking of evapotranspiration. I don't think any of you realize how serious of an influence it is on stationary meteorological station, most of which are close enough to metro areas to be highly influenced.

I have looked and looked. Maybe I'm just not good at searching. All I find is evapotranspiration changes by changing the landscape with things like crops. I have looked for the influence of this phenomena regarding the replacement of the natural landscape with asphalt, concrete, and building.

My searches have yielded no results. Anyone care to help?

I did some quick calculations one day pertaining to where I live in the Portland metropolitan area. We have an average rainfall of 42 inches. Before mankind ever changed the land, a significant portion of this rainfall would end up evaporating from the land, or released from plants into the atmosphere. What didn't return to the atmosphere, would make its way to steams, rivers, etc. and back to the ocean.

I will assume for calculations, with a wide error margin, that 70% of this rainfall would end up back into the atmosphere before 1850, and 20% in present times. This assumes a 50% loss of the evaporative cooling potential from 21 inches of rain for the year in the Portland metro area.

The warmers (deniers of science) will find some way to deny the facts.

To convert to W/m^2, we need the heat of vaporization and seconds per year.

Seconds per year: 31,536,000 (60 x 60 x 24 x 365)

Heat of vaporization: 2257 joules/gram

21" of water represent 0.53 cubic meters. This water weighs 530 kg.

530,000 x 2257 = 1,196,210,000 joules of energy over a 1 meter patch of earth.

1,196,210,000 / 31,536,000 = 37.9 W/m^2 of energy. No wonder the urban heat island effect is so strong.

I'm sure the deniers of science will find reason to scoff at my calculations here, so by all means, do it yourself.

Of course the winds mix the air from areas not affected, but this is a huge change for many metropolitan areas.
 
Lord of Planar said:
Most of you probably remember me speaking of evapotranspiration. I don't think any of you realize how serious of an influence it is on stationary meteorological station, most of which are close enough to metro areas to be highly influenced.

I have looked and looked. Maybe I'm just not good at searching. All I find is evapotranspiration changes by changing the landscape with things like crops. I have looked for the influence of this phenomena regarding the replacement of the natural landscape with asphalt, concrete, and building.

My searches have yielded no results. Anyone care to help?

I did some quick calculations one day pertaining to where I live in the Portland metropolitan area. We have an average rainfall of 42 inches. Before mankind ever changed the land, a significant portion of this rainfall would end up evaporating from the land, or released from plants into the atmosphere. What didn't return to the atmosphere, would make its way to steams, rivers, etc. and back to the ocean.

I will assume for calculations, with a wide error margin, that 70% of this rainfall would end up back into the atmosphere before 1850, and 20% in present times. This assumes a 50% loss of the evaporative cooling potential from 21 inches of rain for the year in the Portland metro area.

The warmers (deniers of science) will find some way to deny the facts.

To convert to W/m^2, we need the heat of vaporization and seconds per year.

Seconds per year: 31,536,000 (60 x 60 x 24 x 365)

Heat of vaporization: 2257 joules/gram

21" of water represent 0.53 cubic meters. This water weighs 530 kg.

530,000 x 2257 = 1,196,210,000 joules of energy over a 1 meter patch of earth.

1,196,210,000 / 31,536,000 = 37.9 W/m^2 of energy. No wonder the urban heat island effect is so strong.

I'm sure the deniers of science will find reason to scoff at my calculations here, so by all means, do it yourself.

Of course the winds mix the air from areas not affected, but this is a huge change for many metropolitan areas.
Click to expand...
With more concrete you would get more evaporation since the concrete does not allow for the moisture to enter the ground, and as we know cities tend to be hotter by several degrees so even more evaporation. So you think more concrete causes less evaporation, am I getting that right?
 
Casper said:
With more concrete you would get more evaporation since the concrete does not allow for the moisture to enter the ground, and as we know cities tend to be hotter by several degrees so even more evaporation. So you think more concrete causes less evaporation, am I getting that right?
Click to expand...

What water settles does evaporate. Problem is, except for small amounts of surface wetting and pooling, nearly all the water today goes into storm sewers, and no longer have the evaporation cooling effect 24/7.
 
What matters is the loss of evaporation cooling equates to about 1.8 W/m^2, for every annual inch of change.
 
Lord of Planar said:
What water settles does evaporate. Problem is, except for small amounts of surface wetting and pooling, nearly all the water today goes into storm sewers, and no longer have the evaporation cooling effect 24/7.
Click to expand...
Ok, but then by being returned to the water ways would not that water still go through the natural cycle? Now if you are talking cooling only for cities then that is the cost of building huge cities and I do not know of anything we can actually do to stem that.
 
Casper said:
Ok, but then by being returned to the water ways would not that water still go through the natural cycle? Now if you are talking cooling only for cities then that is the cost of building huge cities and I do not know of anything we can actually do to stem that.
Click to expand...

I'm not looking to mitigate the warning, rather this warming is one reason why nearby monitoring stations show such unprecedented warming. Most monitoring stations that meteorology relies on to tell us the global temperatures are influenced by their proximity to metropolitan areas. The natural regions of earth, untouched by man, are probably not warming by the amounts claimed for global warming.
 
Lord of Planar said:
I'm not looking to mitigate the warning, rather this warming is one reason why nearby monitoring stations show such unprecedented warming. Most monitoring stations that meteorology relies on to tell us the global temperatures are influenced by their proximity to metropolitan areas. The natural regions of earth, untouched by man, are probably not warming by the amounts claimed for global warming.
Click to expand...

Good point, so one has to look at what is happening globally before coming to further conclusions. Now globally I believe the jury is out on the causes, but the idea that we are warming is pretty much a given.
 
Lord of Planar said:
Most of you probably remember me speaking of evapotranspiration. I don't think any of you realize how serious of an influence it is on stationary meteorological station, most of which are close enough to metro areas to be highly influenced.

I have looked and looked. Maybe I'm just not good at searching. All I find is evapotranspiration changes by changing the landscape with things like crops. I have looked for the influence of this phenomena regarding the replacement of the natural landscape with asphalt, concrete, and building.

My searches have yielded no results. Anyone care to help?

I did some quick calculations one day pertaining to where I live in the Portland metropolitan area. We have an average rainfall of 42 inches. Before mankind ever changed the land, a significant portion of this rainfall would end up evaporating from the land, or released from plants into the atmosphere. What didn't return to the atmosphere, would make its way to steams, rivers, etc. and back to the ocean.

I will assume for calculations, with a wide error margin, that 70% of this rainfall would end up back into the atmosphere before 1850, and 20% in present times. This assumes a 50% loss of the evaporative cooling potential from 21 inches of rain for the year in the Portland metro area.

The warmers (deniers of science) will find some way to deny the facts.

To convert to W/m^2, we need the heat of vaporization and seconds per year.

Seconds per year: 31,536,000 (60 x 60 x 24 x 365)

Heat of vaporization: 2257 joules/gram

21" of water represent 0.53 cubic meters. This water weighs 530 kg.

530,000 x 2257 = 1,196,210,000 joules of energy over a 1 meter patch of earth.

1,196,210,000 / 31,536,000 = 37.9 W/m^2 of energy. No wonder the urban heat island effect is so strong.

I'm sure the deniers of science will find reason to scoff at my calculations here, so by all means, do it yourself.

Of course the winds mix the air from areas not affected, but this is a huge change for many metropolitan areas.
Click to expand...

Urban Heat Island Effect.
 
Lord of Planar said:
What water settles does evaporate. Problem is, except for small amounts of surface wetting and pooling, nearly all the water today goes into storm sewers, and no longer have the evaporation cooling effect 24/7.
Click to expand...

Now you are pissed at concrete and cities where concrete is used?

Is there no end to the hysteria from the loony left?
 
Mac77 said:
Now you are pissed at concrete and cities where concrete is used?

Is there no end to the hysteria from the loony left?
Click to expand...

LOL...

You misunderstand.

I am pointing out the math and science that the warmers ignore when I bring it up. The energy it takes for water to change phases is huge, and the natural cooling that used to be present is disappearing.

I have brought this topic up several times, just for the warmers to deny the science of it.
 
Lord of Planar said:
LOL...

You misunderstand.

I am pointing out the math and science that the warmers ignore when I bring it up. The energy it takes for water to change phases is huge, and the natural cooling that used to be present is disappearing.

I have brought this topic up several times, just for the warmers to deny the science of it.
Click to expand...

Ok

What is your solution to this "problem?"
 
You see, real scientists have never heard of heat islands...


"The preliminary results of an independent assessment carried out by the Berkeley Earth Surface Temperature group, and made available to the public in October 2011, found that among other scientific concerns raised by skeptics, the urban heat island effect did not bias the results obtained by NOAA, the Hadley Centre and NASA's GISS. The Berkeley Earth group also confirmed that over the past 50 years the land surface warmed by 0.911 °C, and their results closely matched those obtained from earlier studies."

https://en.wikipedia.org/wiki/Urban_heat_island#Global_warming
 
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Casper said:
Ok, but then by being returned to the water ways would not that water still go through the natural cycle? Now if you are talking cooling only for cities then that is the cost of building huge cities and I do not know of anything we can actually do to stem that.
Click to expand...

It does return to the natural cycle, but not as much water would have evaporated in the process and the regions dominated by cities will never follow a natural cycle.
 
Lord of Planar said:
Most of you probably remember me speaking of evapotranspiration. I don't think any of you realize how serious of an influence it is on stationary meteorological station, most of which are close enough to metro areas to be highly influenced.

I have looked and looked. Maybe I'm just not good at searching. All I find is evapotranspiration changes by changing the landscape with things like crops. I have looked for the influence of this phenomena regarding the replacement of the natural landscape with asphalt, concrete, and building.

My searches have yielded no results. Anyone care to help?

I did some quick calculations one day pertaining to where I live in the Portland metropolitan area. We have an average rainfall of 42 inches. Before mankind ever changed the land, a significant portion of this rainfall would end up evaporating from the land, or released from plants into the atmosphere. What didn't return to the atmosphere, would make its way to steams, rivers, etc. and back to the ocean.

I will assume for calculations, with a wide error margin, that 70% of this rainfall would end up back into the atmosphere before 1850, and 20% in present times. This assumes a 50% loss of the evaporative cooling potential from 21 inches of rain for the year in the Portland metro area.

The warmers (deniers of science) will find some way to deny the facts.

To convert to W/m^2, we need the heat of vaporization and seconds per year.

Seconds per year: 31,536,000 (60 x 60 x 24 x 365)

Heat of vaporization: 2257 joules/gram

21" of water represent 0.53 cubic meters. This water weighs 530 kg.

530,000 x 2257 = 1,196,210,000 joules of energy over a 1 meter patch of earth.

1,196,210,000 / 31,536,000 = 37.9 W/m^2 of energy. No wonder the urban heat island effect is so strong.

I'm sure the deniers of science will find reason to scoff at my calculations here, so by all means, do it yourself.

Of course the winds mix the air from areas not affected, but this is a huge change for many metropolitan areas.
Click to expand...

It's a very compelling argument and it also extends to other forms of land usage. California's decision to limit water to farmland, much of which evaporates, likely contributes to the drastic changes in California's climate over the last few decades.

I've often thought that the reduction in water to agriculture in California has a negative effect on the west coast water cycle. Evaporated irrigation water travels East to the Rockies, where it condenses to rain and snow and then travels back west and river water. Cutting water to farms creates what I believe is a viscous cycle that, now that I consider your argument, is even worse than I had thought since land warming due to the loss of evaporation means less annual rain as well, which then leads to slower recovery of the aquifer.. and so on.

Americans turned California from a desert into the most productive farmland in the world, and when we remove anthropogenic contributors to California climate the geography of the region pushes it back to desert.
 
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jmotivator said:
Americans turned California from a desert into the most productive farmland in the world, and when we remove anthropogenic contributors to California climate the geography of the region pushes it back to desert.
Click to expand...

I think you're right.
 
jmotivator said:
It does return to the natural cycle, but not as much water would have evaporated in the process and the regions dominated by cities will never follow a natural cycle.
Click to expand...
That I figured would be the case. The only answers to the situation, partial ones, slow the new building and/or requiring that all flat top business buildings have gardens on the roof. So, other than removing mankind, I am sure a pandemic will one day slow the process, mother nature has a knack of removing pests, just kidding, or am I, then we are kinda stuck with it.
 
Casper said:
That I figured would be the case. The only answers to the situation, partial ones, slow the new building and/or requiring that all flat top business buildings have gardens on the roof. So, other than removing mankind, I am sure a pandemic will one day slow the process, mother nature has a knack of removing pests, just kidding, or am I, then we are kinda stuck with it.
Click to expand...

I actually have a cunning plan that I am working on right now to resolve this issue.
 
Mac77 said:
Ok

What is your solution to this "problem?"
Click to expand...

I haven't considered any solutions, because there are few practical ways to stop this. I am merely pointing out that this form of land use change is more dramatic to measured warming than most people think. Also pointing out that it actually skews the assumed global temperature changes due to the proximity of meteorological site locations.
 
Lord of Planar said:
I haven't considered any solutions, because there are few practical ways to stop this. I am merely pointing out that this form of land use change is more dramatic to measured warming than most people think. Also pointing out that it actually skews the assumed global temperature changes due to the proximity of meteorological site locations.
Click to expand...
In others Food For Thought. I found it interesting and may read up more on the subject.
 
Lord of Planar said:
Most of you probably remember me speaking of evapotranspiration. I don't think any of you realize how serious of an influence it is on stationary meteorological station, most of which are close enough to metro areas to be highly influenced.

I have looked and looked. Maybe I'm just not good at searching. All I find is evapotranspiration changes by changing the landscape with things like crops. I have looked for the influence of this phenomena regarding the replacement of the natural landscape with asphalt, concrete, and building.

My searches have yielded no results. Anyone care to help?

I did some quick calculations one day pertaining to where I live in the Portland metropolitan area. We have an average rainfall of 42 inches. Before mankind ever changed the land, a significant portion of this rainfall would end up evaporating from the land, or released from plants into the atmosphere. What didn't return to the atmosphere, would make its way to steams, rivers, etc. and back to the ocean.

I will assume for calculations, with a wide error margin, that 70% of this rainfall would end up back into the atmosphere before 1850, and 20% in present times. This assumes a 50% loss of the evaporative cooling potential from 21 inches of rain for the year in the Portland metro area.

The warmers (deniers of science) will find some way to deny the facts.

To convert to W/m^2, we need the heat of vaporization and seconds per year.

Seconds per year: 31,536,000 (60 x 60 x 24 x 365)

Heat of vaporization: 2257 joules/gram

21" of water represent 0.53 cubic meters. This water weighs 530 kg.

530,000 x 2257 = 1,196,210,000 joules of energy over a 1 meter patch of earth.

1,196,210,000 / 31,536,000 = 37.9 W/m^2 of energy. No wonder the urban heat island effect is so strong.

I'm sure the deniers of science will find reason to scoff at my calculations here, so by all means, do it yourself.

Of course the winds mix the air from areas not affected, but this is a huge change for many metropolitan areas.
Click to expand...

Who in the atmospheric sciences denies evaporative cooling? Don't be ridiculous. The factor is accounted for in the so called "manipulated raw data". The heat island effect is accounted for. No one of the warmers denies any of it. It's recognized and accounted for.

In fact, the same scientific disciplines which learned of this effect so that you could be aware of it, are the disciplines you deniers accuse of covering it up.
 
Russell797 said:
Who in the atmospheric sciences denies evaporative cooling? Don't be ridiculous. The factor is accounted for in the so called "manipulated raw data". The heat island effect is accounted for. No one of the warmers denies any of it. It's recognized and accounted for.

In fact, the same scientific disciplines which learned of this effect so that you could be aware of it, are the disciplines you deniers accuse of covering it up.
Click to expand...

Please show me a paper with the methodology of how its accounted for.

In all my searches, I could never find it.
 
Lord of Planar said:
Please show me a paper with the methodology of how its accounted for.

In all my searches, I could never find it.
Click to expand...
I found this in IPCC AR4,
https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-2-2-2.html
Over the conterminous USA, after adjustment for time-of-observation bias and other changes,
rural station trends were almost indistinguishable from series including urban sites
Click to expand...
But this seems to imply they did not make any adjustment for the Urban heat Island effect.
 
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