Why is ground water in one place a different temperature than groundwater in another?

[Rhea]

I wondered today, as I was waiting for my tap water to reach minimum temperature indicating that all water from the the pipes was out and I was getting fresh groundwater, about the various temperatures of various groundwater.

I went swimming with manatees in Crystal river, FL because the spring water there is 72°F and the manatees like that when the ocean feels cold.

I spoke with a friend in Texas who was lamenting that ice is always needed to make a drink refreshing because the water is so warm out of the ground at 70°F.

And my kids shriek with indignation when I tell them they are too muddy to come inside and I will hose them off with 54°F.

This site shows that it is somewhat latitudinal, but what else do people know about it?

http://www.epa.gov/athens/learn2model/part-two/onsite/ex/jne_henrys_map.html

It doesn't change very much seasonally. Our water is pretty much the same summer or winter. So the weather itself doesn't seem very related. Unless it's just the buffered reaction to the weather not allowing much fluctuation due to dpeth and the insulation of the ground above.

Thoughts?

 

[Rhea]

Also, it is odd that there is a cold spot over Yellowstone, right?

 

[Underseer]

Why would you expect the earth under the ground to be the same temperature everywhere?

 

[Rhea]

Why would you expect the earth under the ground to be the same temperature everywhere?

At a deep enough depth, I do expect that - the conduction of transitional temps from surface less than of heat from center.

What I had not pondered particularly was how deep is "groundwater" How deep are the aquifers. Apparently more shallow than I had thought.
Also I had not pondered how much thermal momentum exists in those shallow layers - enough to mask seasonal changes, but not enough to mask latitudinal differences, apparently.

In the back of my mind I've always known that there is not a seasonal fluctuation in my area, despite surface seasonal temperature changes of more than 120°F. That led to a superficial working assumption that it is a stable thing geographically as well. Until noticing that - it isn't.

 

[Loren Pechtel]

It's basically the average surface temperature in the area.

 

[rjh01]

I would not expect the temperature deep under ground to be the same all the way round the world. For example some parts could have a thin crust, or rocks that conduct heat better or maybe some heat has moved up near the surface.

 

[Malintent]

In NY, my water (city provided, not groundwater) varies radically in temperature from summer to winter... from a cool 65 or so in summer, to near pipe-rupturing freezing in the winter. I can't brew beer in August because the cold water is not cold enough to cool my wort (freshly brewed beer - pre-fermentation) with a heat exchanger from boiling to 62 fast enough (or at all). In the winter it can cool an entire batch in 25 minutes... 5 min under minimum for the correct "temperature crash" (aka "cold break") it needs for that sparkling clarity I look for.

 

[Loren Pechtel]

In NY, my water (city provided, not groundwater) varies radically in temperature from summer to winter... from a cool 65 or so in summer, to near pipe-rupturing freezing in the winter. I can't brew beer in August because the cold water is not cold enough to cool my wort (freshly brewed beer - pre-fermentation) with a heat exchanger from boiling to 62 fast enough (or at all). In the winter it can cool an entire batch in 25 minutes... 5 min under minimum for the correct "temperature crash" (aka "cold break") it needs for that sparkling clarity I look for.

Can't you make an evaporative cooler to cool your cooling water?

 

[bilby]

Why would you expect the earth under the ground to be the same temperature everywhere?

At a deep enough depth, I do expect that - the conduction of transitional temps from surface less than of heat from center.

What I had not pondered particularly was how deep is "groundwater" How deep are the aquifers. Apparently more shallow than I had thought.
Also I had not pondered how much thermal momentum exists in those shallow layers - enough to mask seasonal changes, but not enough to mask latitudinal differences, apparently.

In the back of my mind I've always known that there is not a seasonal fluctuation in my area, despite surface seasonal temperature changes of more than 120°F. That led to a superficial working assumption that it is a stable thing geographically as well. Until noticing that - it isn't.

The water coming out of your taps has its temperature determined by the temperature of the ground at the depth of the supply main. It is not so important what the temperature of the aquifer or the reservoir feeding that main might be; long thin pipes at about a metre below ground level will supply water at the mean temperature of the ground at that depth. (in Sydney, the required depth is 450-700mm for pipes not under roadways; 600-750mm under most roadways, and 1200mm under freeways and major highways).

This is shallow enough to be relatively unaffected by geothermal factors (except in very high activity locations); and deep enough to insulate against most seasonal variation - except in places with continental rather than maritime climates, where seasonal variation is very large.

Earth is quite a good insulator, but also has quite a large heat capacity; when the London underground was first built, people would remark on how cool the stations were, due to being buried under the surface; but now that 150 years of heat from trains and passengers has accumulated, many stations are uncomfortably hot, and the authorities are constantly seeking ways to get that heat up to the surface. Some trains have heat pumps on board, that act to cool the tunnels from on board tanks of chilled material, and reverse themselves on the overground sections, using the same heat pumps to re-chill the substrate for the next underground leg.

Overall, the temperature of the water is buffered to remain very close to the mean surface air temperature in the region.

I recall my first wife, who grew up in Brisbane, was surprised that our hotel in New Zealand didn't have chilled tap water - until she found that the tap water came out of the tap at about 6^oC, and is quite drinkable. In Brisbane, tap water is unpleasantly warm, and not very refreshing unless chilled.

 

[bilby]

In NY, my water (city provided, not groundwater) varies radically in temperature from summer to winter... from a cool 65 or so in summer, to near pipe-rupturing freezing in the winter. I can't brew beer in August because the cold water is not cold enough to cool my wort (freshly brewed beer - pre-fermentation) with a heat exchanger from boiling to 62 fast enough (or at all). In the winter it can cool an entire batch in 25 minutes... 5 min under minimum for the correct "temperature crash" (aka "cold break") it needs for that sparkling clarity I look for.

I use 15kg of ice for each batch of beer. There is no way the local water would ever get the wort cool enough here, even in winter.

 

[Loren Pechtel]

Earth is quite a good insulator, but also has quite a large heat capacity; when the London underground was first built, people would remark on how cool the stations were, due to being buried under the surface; but now that 150 years of heat from trains and passengers has accumulated, many stations are uncomfortably hot, and the authorities are constantly seeking ways to get that heat up to the surface. Some trains have heat pumps on board, that act to cool the tunnels from on board tanks of chilled material, and reverse themselves on the overground sections, using the same heat pumps to re-chill the substrate for the next underground leg.

Yeah. One interesting idea in home construction I've run into: Put it a bit underground, put a waterproof layer extending several yards beyond the edge of the house. In most climates this produces a house that will remain comfortable without AC or heat, just some fans connected to long pipes through the ground. The idea is the thermal capacity of the ground is enough to moderate the swings, so long as it's swinging back and forth around a reasonable value it works.

 

[Malintent]

In NY, my water (city provided, not groundwater) varies radically in temperature from summer to winter... from a cool 65 or so in summer, to near pipe-rupturing freezing in the winter. I can't brew beer in August because the cold water is not cold enough to cool my wort (freshly brewed beer - pre-fermentation) with a heat exchanger from boiling to 62 fast enough (or at all). In the winter it can cool an entire batch in 25 minutes... 5 min under minimum for the correct "temperature crash" (aka "cold break") it needs for that sparkling clarity I look for.

Can't you make an evaporative cooler to cool your cooling water?

sure... I have many options... but my simple immersion cooler (poor man's HEX) is my most economical option.
I could also use ice, refridgerated water, or a better HEX with more surface area and circulation. I just take the summer off.

 

[Jimmy Higgins]

Earth is quite a good insulator, but also has quite a large heat capacity; when the London underground was first built, people would remark on how cool the stations were, due to being buried under the surface; but now that 150 years of heat from trains and passengers has accumulated, many stations are uncomfortably hot, and the authorities are constantly seeking ways to get that heat up to the surface. Some trains have heat pumps on board, that act to cool the tunnels from on board tanks of chilled material, and reverse themselves on the overground sections, using the same heat pumps to re-chill the substrate for the next underground leg.

Yeah. One interesting idea in home construction I've run into: Put it a bit underground, put a waterproof layer extending several yards beyond the edge of the house.

Waterproof layer? As in trying to cap the ground surface and limit water percolating into the ground from precipitation? Is this a soil layer, a fabric? And what does water have to do with it?

In most climates this produces a house that will remain comfortable without AC or heat, just some fans connected to long pipes through the ground.

Isn't the ground closer to 55 to 60 degrees at shallower elevations? Don't see this helping in the winter.

 

[Loren Pechtel]

Yeah. One interesting idea in home construction I've run into: Put it a bit underground, put a waterproof layer extending several yards beyond the edge of the house.

Waterproof layer? As in trying to cap the ground surface and limit water percolating into the ground from precipitation? Is this a soil layer, a fabric? And what does water have to do with it?

The soil is only a good enough insulator when it's dry.

In most climates this produces a house that will remain comfortable without AC or heat, just some fans connected to long pipes through the ground.

Isn't the ground closer to 55 to 60 degrees at shallower elevations? Don't see this helping in the winter.

It provides enough thermal mass that you get the year-round average temperature, although the house will be warmer because it's occupied.