57
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Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
Water is a rather strange substance. With most substances, the solid phase is denser than is the liquid phase. This is not the case with water. Ice is less dense than liquid water. A side effect of ...
- 22.4k
53
votes
Accepted
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
Water melts at 0 °C (32 °F) but freezing is a more complicated affair. It is safe to say water gains the ability to freeze at 0 °C, but it can get much cooler before it actually does so resulting in ...
- 14k
45
votes
Why doesn't the 71% water of the earth dry or evaporate?
There are two ways this problem needs to be looked at. The first is more astronomy than Earth science. The Earth as an entire system is largely contained. Its gravity and magnetic field retains ...
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39
votes
Why does the salt in the oceans not sink to the bottom?
When dissolved in water, salt breaks up into sodium and chlorine ions, which combine with water molecules so they cannot easily sink. However, there is a tendency for streams of fresh water to float ...
- 4,507
38
votes
Antarctic and arctic meltwater is "bad" because it's dark, but why is transparent liquid on white stuff so dark?
Water has lowest EM absorption in the blue part of light spectrum and increases rapidly towards both UV and red parts of spectrum.
As a result in visible light water is blue. Same goes for the ice ...
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34
votes
While desalinating ocean water, would it be bad if we didn't pump the brine back into the ocean?
What does it take to reduce the salinity?
The salinity of sea water is around 35 g/kg. There are around 1,350,000,000 km³ of water, so roughly 1.3x1021 kg of seawater (1 kg/l, which is a bit off for ...
- 441
30
votes
Why does the salt in the oceans not sink to the bottom?
Why does the salt in the oceans not sink to the bottom?
Because there isn't any "salt", per se, in the ocean. Salt, as the compound sodium chloride (NaCl) does not exist as a solid in the ocean. It ...
- 22.8k
29
votes
Is a complete global flood physically possible on Earth?
Just to add some further discussion to @Pont and @fre0n excellent answers.
The problem of the water needed to submerge the world during the Genesis flood have been discussed for centuries. The ...
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28
votes
How can we have groundwater depletion when the Earth is 78% covered with oceans?
How can we still lack groundwater?
That 71% of the Earth's surface is covered by oceans is completely irrelevant to the issue of fresh groundwater depletion. Salty groundwater is useless for drinking ...
- 22.4k
25
votes
Accepted
Is it possible for rivers to freeze completely and stop flowing?
I am interpreting your question as referring to rivers with flowing water freezing as as opposed to glaciers, which are already frozen.
Under current climatic conditions, small rivers can freeze ...
- 23k
25
votes
Why doesn't the 71% water of the earth dry or evaporate?
Why doesn't 71% water of the earth dry or evaporate?
The simple answer: Because it rains.
The not so simple answer: By some estimates, the Earth has already lost about a quarter of its water, and it ...
- 22.4k
23
votes
Accepted
Is a complete global flood physically possible on Earth?
there is not enough existing water inside this geosystem IMO for such a thing to occur. Let's see these figures here:
One estimate of global water distribution
Oceans, Seas, & Bays 1,338,000,000 ...
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22
votes
Is a complete global flood physically possible on Earth?
The "precipitation rate" part is easy to answer, at least to a first approximation. We have 40 days and nights (960 hours) in which to raise sea level above the peak of Mount Everest (let's round up ...
- 5,401
22
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Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
Due to convection (the cold water sinks while the warm water rises), the entire pond needs to be brought to near-freezing temperatures before the surface can freeze. With only the top of the pond in ...
19
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While desalinating ocean water, would it be bad if we didn't pump the brine back into the ocean?
The residue dry powder you refer to is salt.
Salt is toxic to most plants. The United Nations claims the world is already losing 2000 hectares per day of farm land to salt-induced degradation. This is ...
- 23k
17
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Antarctic and arctic meltwater is "bad" because it's dark, but why is transparent liquid on white stuff so dark?
"Transparent" is not the same as "white" : white bodies reflect most of the light while transparent bodies let the light though. Once the light enters into water, it may need to travel a long way ...
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16
votes
How is it possible to use up the water in a region?
This is a really complex problem and would require a really detailed explanation about atmospheric circulation, meteorology and hydrology.
The short answer to your question is that water is going ...
- 1,258
15
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
The water in a pond is in contact with the ground and the ground is not even close to freezing even if the air temperature is 27° below freezing.
- 2,157
15
votes
What would be the effect of bringing seawater pipes to the Sahara desert?
This is an interesting question & I've been waiting to see what answers, if any, would be written.
One affect of creating such a lake would be a localized increase in humidity in the vicinity of ...
- 23k
15
votes
Accepted
Ground water is almost every where, then how do mines and other holes are digged so that ground water doesn't drain into it
We pump it out. Open and closed pit mines usually have pumping installations to get the water out.
Look up Mine dewatering on Wikipedia.
There have also been numerous accidents in the past where ...
- 2,657
14
votes
Accepted
Water veins underground causing health problems
In my opinion, there is no such thing as water veins as described in this article, but, it is a fact that there is water circulation underground.
In the natural environment, water can either ...
- 2,623
14
votes
Accepted
How is it possible to use up the water in a region?
You're making a mistake, at least for the second case:
In the second case, the water ends up as rain, presumably within a few hundred kilometers of the evaporation point.
You cannot model a dry ...
- 11.4k
13
votes
Accepted
How much water is the atmosphere losing to space?
It is not actual water what is lost to space, because in the high atmosphere water usually dissociate into other molecules or ions. The oxygen ion outflow is frequently assumed to be a proxy for the ...
- 17.3k
12
votes
Is this ice cover real - and what circumstances are required to make it?
Yes, it is real. Whoever took the photo, congratulations on a very fine image.
I have never seen this texture on such a scale, but something similar can be achieved in the laboratory by creating a ...
- 14.1k
12
votes
Accepted
Water on Mars and Earth
If water on Earth came from meteorites, why doesn't Mars have substantial water?
First off, that's a conjecture regarding the origin of the Earth's water rather than a known fact. A few times a year ...
- 22.4k
12
votes
Accepted
Will the oceans swallow all of the land?
If no new mountains were built, yes. Ultimately the processes of erosion would render the continents flat, and the seas would be left shallow and filled with sediments. The reason that this doesn't ...
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11
votes
How much land does it take to support New York City?
The average ecological footprint of a US citizen has been estimated as 8.00 global ha.
Multiplying 8.5 million by 8.00 hectare gives 680,000 km², or around 5 times the area of New York state.
Of ...
- 11.4k
11
votes
Is it possible for rivers to freeze completely and stop flowing?
In a way, glaciers are just like frozen rivers. A good start on that topic comes from USGS. Ice (whether in a frozen river or in a glacier) is still a fluid and thus is always moving because of its ...
- 15.3k
11
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If water is a renewable resource, why is there water scarcity?
What I miss in the other answers is water quality.
Even is there is sufficient water available it is often of insufficient quality for the purpose you want it for:
We often don't drink straight out ...
- 2,657
11
votes
Why does the salt in the oceans not sink to the bottom?
I'm a regular from the Physics Stack Exchange reporting for duty.
Why this is a serious question
This is a bigger question than you might be giving it credit for. The question is ultimately similar ...
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