57
votes
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 ...
- 23.2k
56
votes
Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?
This is due to thermodynamics, the three laws of which can be summarized as 1) You can't win; 2) You can't even break even; 3) You can't leave the game.
The crucial point here is that heat engines don'...
- 1,748
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 ...
- 14.1k
34
votes
Accepted
Do fossil fuels insulate the crust from the Earth's interior?
Quoting from John Russell's response to this article, "This is arrant nonsense!"
Russell concludes with
How did this paper get through the peer-review and editorial review processes? What ...
- 23.2k
32
votes
Accepted
Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?
Collecting thermal energy is really hard. As others have said, things like heat pumps exist for moving heat around, but the laws of thermodynamics (which are fairly fundemantal in physics) require ...
- 5,800
22
votes
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 ...
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.
- 2,177
15
votes
Accepted
Why does it rain more at night than during the day?
First off, your observation that Tamil Nadu gets more rainfall in the evening is partially backed by records. Sahany, Venugopal, and Nanjundiah, 2010 provide data on diurnal scale rainfall ...
- 3,366
15
votes
Do fossil fuels insulate the crust from the Earth's interior?
What neither the authors nor the response by John Russell takes into account is that all underground oil and gas is stored inside tiny pores of rocks. An oil reservoir is not a big underground cave, ...
- 251
15
votes
Accepted
Is the global temperature of the earth a physical quantity at all?
There is no unique way to define a global average temperature of the Earth, but that does not mean that calculation of such a quantity is "pointless". If someone tells me that the average ...
- 813
14
votes
Sea Level Rise due to Climate Change
The first part of the association is that increasing levels of greenhouse gases in the atmosphere will cause rising temperatures on earth. Here is some information on why that is so, if you are ...
- 3,366
12
votes
Is global warming being moderated by latent heat of melting polar ice?
Latent heat is a factor, but is completely eclipsed by the rate of global warming.
For example, since 1978 the April (maximum) Arctic sea ice has decreased in volume by about $11,000$ cubic km. The ...
- 14.2k
11
votes
Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?
Like passive radiative cooling?
The new materials reflect a broad spectrum of light, in much the same way as mirrors or white paint do. In the crucial 8–13-µm part of the infrared spectrum, however,...
- 211
10
votes
Accepted
First to Sail the Jet Stream Around the World
As your diagram shows, the jet stream actually has two circulating components: one is "around the earth" (which is why the transatlantic crossing is so much faster going East than going West), while ...
- 1,374
10
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
This could be because the air cools and heats faster than water. Air has a lower Specific Heat than water. It may take some time for the water to freeze.
- 201
7
votes
Accepted
Why doesn't subducted earth crust melt?
...the submerging plate is always drawn as deep (seemingly tens of km) into molten rock...
It's actually hundreds of kilometres, not tens of them. But let me correct a common misconception:
The ...
- 23.1k
7
votes
What is the average temperature of the whole planet Earth, not just the surface?
TL;DR:
Approximately $2700\,\text K$ ($2400\text{°C}$, $4400\text{°F}$)
Assuming that the weights are indeed the heat capacity per unit volume $C$ and that $C \approx \rho C_P$, where $\rho$ is the ...
- 241
6
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
The variable you need to consider to understand the problem is the pond's depth. I bet that in contrast to your pond, shallow puddles around did freeze.
The water is denser at 4°C, so to freeze the ...
- 17.6k
6
votes
Sea Level Rise due to Climate Change
It's a harder direct relation to show that it appears. On the surface, warmer = less ice, file under "duh", but while it probably is that simple, showing a causal relation is a more difficult.
The ...
- 5,847
6
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
No-one has mentioned fish yet. Do you have fish or other animals in your pond? Not only do they provide a small amount of warming, their movement will help prevent ice forming.
- 161
6
votes
Accepted
A balloon falling from space?
You cannot leave "temperature outside", as temperature is the key factor to know if the balloon would pop or not.
Let's set up some assumptions about the problem so we can calculate something:
The ...
- 17.6k
6
votes
Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?
As others have pointed out, if you use the energy, it turns right back into heat.
Radiating it back to space is at least theoretically possible. But there is a problem with scale.
The Earth ...
- 221
5
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
In addition to the accepted answer from Casey, it is likely that the sun is warming the pond over the course of a day more than it warms the thermometer used for the temperature readings you are ...
- 191
5
votes
Please help in understanding redox buffers
First let me start by saying that redox buffers are a made-up thing. All these QFM (actually FMQ) or NNO or other abbreviations don't exist in nature. They were developed as a way to "cheat" in ...
- 23.1k
5
votes
Accepted
Sensible and Latent Heat. how to separate them
First some definitions:
Latent heat is the heat that leaves or enters a system during a process where the temperature of the system stays constant. Phase changes are prime examples where latent heat ...
- 450
4
votes
Is global warming being moderated by latent heat of melting polar ice?
This IPCC graph (discussed here) shows the amounts of heat going into oceans, atmosphere, land and ice melting.
Plot of energy accumulation in zettajoules within distinct components of Earth’s ...
- 2,369
4
votes
First to Sail the Jet Stream Around the World
Keep in mind that your jetstream map is only a schematic description. In reality you will experience shear (strong wind along jet axis, decreasing outwards).
Assuming that the airship would drift ...
- 438
4
votes
what is the best way to actually make the Earth lose heat?
What is the best way to actually make the Earth lose heat?
TL;DR: Stop pumping so much carbon dioxide into the atmosphere.
The easiest approach in terms of human effort would be to let the Earth ...
- 23.2k
4
votes
Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?
Just to hammer it down: the amount of energy transferred to Earth by the sun every single day is colossal. In comparison, the heat generated by all human activities is negligible.
For instance, ...
- 141
3
votes
Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?
The question doesn't say if the pond is stream fed. If it is groundwater fed - it will take much longer to freeze, due to the fact that the groundwater is moving through an insulated body (ground) and ...
- 31
Only top scored, non community-wiki answers of a minimum length are eligible