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38

When the ambient humidity is high, the effectiveness of evaporation over the skin is reduced, so the body's ability to get rid of excess heat decreases. Human beings regulate their body temperature quite effectively by evaporation, even when we are not sweating, thanks to our naked skin. (This, supposedly, is also what made it possible for early hominids to ...


28

Law of Thermodynamics says that two bodies eventually will have equal temperatures. That is not an absolute Law. There are conditions, and one of those conditions involves the energy input to the bodies. If this Law was absolute, then the Sun would be at the same temperature as the universe, about 2.7 K, because the universe is much larger than the ...


8

It because the higher humidity makes it more difficult to cool the body. Even though the room temperature is below body temperature, you generate more heat than needed to maintain your body temperature. To help cool you down, you sweat, and the water evaporates from your skin. The evaporation of the water cools you down. When the humidity is higher, the ...


7

While respecting the other good and thoughrough answers, I feel I can give you a simple explanation to your exact question. The 0th law of thermodynamics is the law of the temperature balancing that you refer to. As you mention in your question, this law says that two bodies eventually will have equal temperatures when in thermal contact. "Eventually" is ...


5

The air has very low thermal conductivity and capacity, in most cases outside, the main contributor to thermal exchange (and thus perception of temperature) is radiation (Stefan's law, every object is radiating light all across the spectrum, with colder bodies giving most of it in infrared, hotter is more visible red (coal embers, hot iron), then yellow, ...


4

Perhaps because of the same reasons as the warming of greenhouses? If the windows are uncovered the sunlight increase the energy inside, by isolating the warm air inside the structure so that heat is not lost by convection. [From Wikipedia]


3

For the thought experiment in your question, the answer is: it depends on the temperature of the room! Cold Room If the room is cold, humidity will actually make it feel colder! This is because water vapor has a much higher heat capacity than dry air, meaning that it takes more heat to raise or lower its temperature. So a volume of air with a lot of water ...


2

"Thermal energy" is a bit of a misnomer because "thermal" really refers to a method of energy transfer, not energy storage. When energy moves from one system to another, it can do so via a thermal process (e.g. conduction, convection, radiation) or a mechanical process (something pushes on something else). So technically, I wouldn't call $\frac{3}{2}kT$ the ...


2

That's not an easy one... First of all you must know the final temperature you are trying to achieve, then you need to choose a heat source and a way to trap heat where you need it I'd sugest you build a "soup-can forge" or something like that and use a MAP-gas torch. A J23 ceramic hoven brick might also be a good choice, maybe even easier to make. With ...


2

The way to understand this is as follows. Assume that the early-universe is radiation-dominated, and additionally assume that the early universe is of FLRW type with a single fluid that obeys a barotropic equation of state $p = w \mu$ where: $w = 1/3$ for radiation $w=0$ for dust $w=1$ for a stiff fluid, etc... Now, the Einstein field equations ...


2

Really, your confusion is rooted in the fact that the equation you give relating temperature and particle mass assumes that the thing's whose temperature you're predicting is a gas of particular matter that obeys Newtonian mechanics. Light, and really anything in the early universe, decidedly does not obey Newtonian mechanics. There are several ways one ...


2

Imagine wind blowing along a plane with the air by the ground all a nice and steady temperature. Now this wind encounters a mountain range, so is forced upwards. The pressure is lower at higher altitude since there is less remaining atmosphere above it. The temperature of gas decreases when the pressure is lowered, which is why this same air gets ...


2

An atmosphere in absolute equilibrium in fact is isothermal (see below for more detailed analysis of your cannonball). However, if the atmosphere is mixed by wind, gas expands and contracts adiabatically. If the mixing is fast enough, it obeys relatively well the adiabatic invariant, which multiplied by suitable form of ideal gas law ($(T/(pV))^\gamma = ...


2

Why it is colder in mountains, at high altitudes? One answer is that mountains on Earth aren't all that tall. An impossibly tall mountain would see temperatures vary with altitude as depicted below. Tall as it is, even Mount Everest doesn't extend into the stratosphere. This is a question about the lowest layer of the atmosphere, the troposphere. ...


1

The air becomes colder because of the ideal gas law, $PV=nRT$. where $P$ is pressure, $V$ is volume, $n$ is the number of moles of the gas, $R$ is the ideal gas constant, and $T$ is the temperature of the gas in Kelvin. If we rearrange $PV=nRT$, we can solve for $T$. By looking at $T=\frac{PV}{nR}$ you can see that reducing pressure will reduce the ...


1

From Psychrometry in Refrigeration & Air Conditioning Let $t_d$ be D.B.T. (dry bulb temperature) & $t_w$ be W.B.T. (wet bulb temperature) and $p_s$ & $p_w$ are saturation pressures at D.B.T. & W.B.T. respectively (refer to "Steam Table" for saturation pressures at given temperatures) then using Carrrier's Equation, the partial pressure ...


1

Not sure the calculation was done correctly (on first glance). However, that is not important here, just think about what you are doing: You have N particles all of which are mutually interacting via a super-long-ranged potential (Coulomb-interaction $\sim r^{-1}$ would be considered long-ranged, you are using a parabolic $\sim r^2$ potential). So, what you ...


1

as molecules jump higher, they loose energy/speed due to gravity. This results in molecules slower at heights and therefore you have lower temperatures at the heights, boy. Molecules do not jump up, they scatter off each other every which way. The difference in gravitational energy within the nanometers of the molecule's path before a scatter on ...


1

I don't see anything wrong except the extra minus sign. The idea that heat gained equals heat loss is spot on but both quantities need to be positive in this case. One way I like to think about this would be that the change in heat of the metal plus the change in heat of the water must add to zero. In this equation, "H_metal + H_water = 0", the sign of ...


1

The energy per time ("power") in the radiation due to heat ( the infra-red "light" that you see using a night vision) scales with the temperature $T$ of a body like $T^4$



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