A heat pump is a machine that moves heat from one place to another. Instead of using energy to heat up cold air, it takes the heat out of ambient temperature air and moves it to air somewhere else. These leaves the original air cooler than it was before, while the other air is now warmer. In case you're wondering, it does consume energy to move heat and create a temperature differential, but a heat pump consumes much less energy than it would take to just heat up cold air. Something interesting I found out, there is a natural weather phenomena that acts like a heat pump. If any of you live just east of the Rocky Mountain range, you may be familiar with the Chinook winds. In Spring these winds can suddenly change the weather from cold to warm and dry. These winds come from the mountains. Which you might find strange. Why would winds that come from the mountains be cold? When air flows over a mountain range, it is temporarily pushed up to a higher elevation. Higher up in the atmosphere the air pressure is lower. When air expands, it becomes cooler. (This is because there is more space between molecules, so they can bounce around more and hold more energy) When air is compressed, it becomes warmer. (Basically the heat is squeezed out of it) So when air blows over a mountain range, it would cool as it goes up, and then warm back up as it comes back down. However, the air coming from the Pacific, from the west, is warmer and full of humidity. When water vapor condenses out of the air into droplets of liquid, it results in a heat increase. (This shouldn't be surprising, it's kind of like the reverse of boiling water) So when the air moves up the mountain and lowers in temperature, it releases rain, loses water vapor, and does not lower in temperature as much as it otherwise would. This sets the stage for even warmer temperatures when that air comes down the other side of the mountain. Indeed, the wind can be a warmer temperature when it gets through to the other side of the mountain than it was before it went up the mountain. The water, which condenses from a vapor to liquid, basically acts in this situation analogous to a coolant in an air conditioner.
I live where we get the Chinook winds from time to time. The folks who grew up here always looked forward to when they could go outside and play in the dead of winter in shorts and tee-shirts for a few hours when the Chinook Winds picked up.
If you pilot a plane, you’d know warm air is less dense than cold air, why warm air rises. Warm air being less dense, results in sluggishness air control surfaces and generates less lift in takeoff and landing because the negative effect of ground effect that is generated on the less dense cushion of air between the wings and the ground. The same plane reaching sluggishly near the ground in warm air wii feel far more responsive as you increase in altitude and they air cools and become more dense. This effect can be dramatic to the point where the weight of cargo carried can impede lift to the point where takeoff can be a dangerous proposition. Also, a warm air mass, relatively speaking, can hold more moisture than cool air. An air mass being pushed over a mountain cools and as it reaches a threshold temperature, the water vapor begins condense and when too heavy to be suspended, fall in the form of rain or snow. Then as the pushed cool air reaches the peak of a mountain and crosses on the lee side of the mountain it has released all the moisture it can hold at that elevation and temp, it begins to fall and warms at a predictable rate. It’s why, as a skier, you’d recognize the deepest snow is opposite the lee side. There are times, again, a skier would know, that on hitting the peak and falls to the Lee side, if it hits a cooler air mass the result can be fine powder. If it hits a warmer airmass, the cooler air can result in the warm air mass to release it’s moisture resulting often in a wetter snow. Their are variations, for instance, air pushed to rise from a desert will still contain moisture, but less than an air mass flowing from the ocean, and as the air from the desert ascends and cools, it can result in a very fine power... one the the reasons Taos New Mexico’s (my favorite) an the ski ares east of Salt Lake have fame for their powder. Flying in the mountains can be tricky, opposite the Lee side, air can rise so quickly it can be a challenge to maintain a consistent altitude, but a very dangerous condition is air on the Lee side can deceptively fall (not talking wind here) faster than some small plane pilots realize. Lots pilots have died because of it. It is speculated Steve Fosset died that way. Some pilots, including of commercial planes, get caught in a down draft, and when they become aware of the situation, they attempt to climb, not realizing the down draft exceed their rate of climb. The proper, and not intuitive response is not to climb, but and fill power and dive (obvoiously not always possible depending on the proximity of the ground) to gain airspeed that enables you to exceed the rate of air mass fall, and fly out, of the descending air mass. I almost bought the holo when getting in a down draft hang gliding on a mountain out west and getting caught in such a down draft (my fault entirely; I ignored to posted warning to get a flight in on my last day). It was very scary, I dove, flying faster in that Kit than I ever had, wondering at the time if the kite could take the strain. I when from about 4,000’ to valley level in seconds ...or so it seems, to emerge within a too close 1-200’ to land a long way from my car and call it a day... too scared to pucker.
But that's kind of irrelevant to the effect we are talking about here. However, I will say that sometimes during Chinook winds, the warm air will form a layer over cold air that was already there, so mostly only hill areas that are above the flat plains will experience a rapid increase in temperature, when the wind comes through. But actually, it is not entirely irrelevant, because it does help explain why it takes energy to go into the system to move heat. When the wind is blowing up the mountain, the air cools as it rises, so mathematically some of that wind energy would be lost pushing cool air upwards. The warm air, presumably, falls down the mountain, rather than rising, because of a pressure differential. The cold air that was already there is pushed out of the way (and pulled upwards by Bernoulli's principle), which would draw more air from down the mountain, even if that air is warmer and lighter. There would also be a pressure increase on the top of the mountain (relative to the lower pressure of the air already up there) that would help push air down. (Or if you want to think of it in one way, gravity)
I also apologize, the opening post got posted before I was finished completing it and editing it. There was a computer problem, and then I was not able to finish adding everything and correcting mistakes before this forum prevented any more editing due to an automatic programmed time limit. For example, one of the lines should have read: "Which you might find strange. Why would winds that come from the mountains not be cold?
Air pressure decreases with altitude, not increase. Air masses at sea level in essence bear the weight of the columns of air above. Air at the surface can be differentially heated by solar energy based how much solar energy heats the surface, and then radiated heat in turn heating the air in close proximity, causing to expand and rise. There are occasions where the surface is snow covered in winter and solar energy is reflected rather than absorbed, heating the surface, and then the surface cools the air at a greater rate the the normal cooling associated with an increase altitude creating what is called an inversion, which, if their are no winds, an stagnated conditions can often trap pollution. From a distance you can often see this effect when flying to Cities like L.A. Certain surfaces can be heated more or less depending on whether light is reflected or absorb. Pockets of differentially heated surfaces can result in turbulence, some times significant at altitude; most here have experienced that phenomena while flying. It, pockets localized rising and falling air at altitude is often greater in the summer and above urban heat sinks, particularly in small private planes and also over mixed composition mountains with massive rock surfaces vs forested ground surfaces. Air masses falling after being pushed over an a mountain, will warm as they descend. In general, for every 1000’ in elevation the temperature changes 3.3-4*. One reason if a pilot sees Ice accumulation forming (dangerous not because weight, but because it disrupts air flowing over the wings and impacts their ability to create lift) a pilot will descend to warmer air. Every pilot gets detailed weather prediction and actual observations reported by other pilots prior to flying and often on a continual basis during a flight. Rising or falling air doesn’t create wind, wind is created by differences over very large areas, with some areas relatively predictable such as the polar regions (high pressure), Greenland or areas of low pressure Caribbean, tropics, etc. these centers shift with the season and the variable heating of the earth’s surface. Much of the similar mechanic of the atmosphere can be seen in the water columns and oceans. For a natural heat exchange engine particularly homes and business, in recent years are more and more people are installing geothermal systems. Query geothermal system for homes to see explanations of the mechanics and the businesses specializing installing them. They work best in high heat gradient areas.
I think maybe you didn't understand what I was saying. If air pressure is higher than it otherwise would normally be at that altitude, some of it will be pushed down, even if the air is lower in pressure than the air below it. This is ultimately caused by gravity, the same thing that leads to pressure differences based on altitude in the first place.
Sure you wanna hang with that? Because strictly interpreted, the claim is unphysical. Boiling water results in a heat decrease?
It's true, but perhaps not stated the best way. When rain condenses from clouds, it does result in an increase in temperature. But it would be more representative to say that water vapor in air acts as a buffer to prevent the temperature from going down, since as heat energy is lost, instead of the temperature going down, water vapor condenses to liquid. As the humid air ascends up the mountain, it doesn't lower in temperature as much as it otherwise would.
Let me try to explain it to you this way: Water absorbs heat energy when it is boiled. Water vapor releases heat energy when it turns into a liquid. If you take a kettle of water with a thermometer in it and heat it on the stove, the temperature of the water will gradually start going up, until it reaches 100 C. At that point, the temperature will remain at 100 C until all the water has boiled off. Heat energy is being added, but the temperature does not increase. That's because the heat is being absorbed by the water as it turns to steam. In a similar fashion, if you had a pipe full of hot steam, it would take a lot less cooling to lower the temperature from 105 C to 102 C than to lower the temperature from 101 C to 99 C. (This is just an analogy though, we should not completely confuse water vapor with steam. It takes a lot less energy for air to absorb water vapor from liquid water than it does to boil water)
More accurately, it releases heat from the time it first evaporates to the time it starts to condense, at which point it has lost all it gained by evaporating originally - which is, after all, why it condenses. So at the point of the phase change it has no more energy to impart to the air than a bullet fired upward has, at its apex, upward momentum to impart to another object.
I had a similar experience on an ifr approach over mountains when I was pretty nubbie. I was full power and max climb, but descending at about 500' per minute. The controller called me on being below the approach. It was night and rainy - not as if I could change course and I knew little about mountain flying. I'm still here. But, I spent some serious study time after that!
One of the Noah issues. Raining 40 days and nights enough to flood like that would release a stupendous amount of heat. Surely before then it would have to simply stop raining. If not, one would wonder how Noah survived the heat.
Yeah, you can study all you want when new to flying, but some things you don’t internalize until you have gone through an experience and either figured it out or got lucky. Common intuition doesn’t apply to flying. It’s why I paid for an instructor way beyond my license to put me through various emergency scenarios (many of which he did without letting me know what was coming). Funny, many things I learned or should say internalized while hang gliding at Torrey Pines just outside La Jolla. I have had more than one scary experience, including one similar to yours, but not at night with rain... why am I still descending at full power...pucker....Lol
