I was under the impression that water becomes steam only because its under pressure remove the pressure and it cools quite quickly because its no longer under pressure.
Oh I see where your misunderstanding is coming from now.
Water becomes steam (converts from liquid to gas phase or boils) depending on pressure and temperature. At sea level, (one atmosphere) it becomes steam (gas) at 100 degrees C. If you move it up a high mountain then it boils at a much lower temperature.
Put it in a vacuum and it instantly boils no matter what the temperature is. Pressure is the only thing that keeps it liquid.
Have a look at the
phase diagram for water/ice/vapor
Please explain black radiation making it not possible for steam to cool quite quickly in the natural once its pressure is removed as in a vacuum as stated in the article that it cools quite quickly to 46 degrees F to a clear chilled water vapor.
As for the temperature, that is down to the rate of molecular vibration and is independent of pressure entirely. The water molecule can only get rid of its heat (vibration) by passing it on to something else. In a vacuum there is nothing to pass it on too except for infrared low energy photons (black-body radiation) so it will remain very very hot for a long long time.
Gasses always want to expand to fill up all available space around them in order to equalize pressures. In space the volume to fill is pretty much infinite so the molecules will continue to move away from each other until they no longer interact with each other in any way. The vast majority of the stuff would never return to earth at all once it gets into space.
Explain why I need to keep heating my hot water heater if this black radiation takes so long to dissipate its heat.
because your hot water tank is NOT in a vacuum and can therefore lose heat to its surroundings by conduction. The pipes that come out of it
feel hot right? That is conduction.
The compressed air enters the nozzle at ambient temperature but as it expands into the open air, this high-density air cools dramatically. It is doing work on the open air, pushing that open air out of its way to make room for itself as it expands to normal density and pressure. Doing this work takes away a good fraction of the compressed air's thermal energy, so it becomes quite cold. Heat flows into it from the water droplets and those water droplets freeze into artificial snow.
This is basic physics. Nothing tricky here.
and incidentally this is not the entire quote from your site. it makes more sense with the entire thing included.
First it asks the question.....
quote:
To speed the freezing process, the jet from the water nozzle mixes with the jet from a compressed air nozzle. Air spraying out of this second nozzle not only breaks up the water into tiny droplets, but it helps to cool and freeze those droplets as well. However, the compressed air and the water both enter their nozzles at the same temperature--about 0 C. Explain how this expanding jet of compressed air is able to help chill the water jet.
then it goes on to answer the question...
quote:
Answer: The expanding air does work on the surrounding air and its temperature decreases as a result. Heat flows out of the water jet into this expanding jet of air and the water freezes into ice
The jet of air absorbs heat from the jet of water as it expands.
In this example the air starts out at ambient temperature (which is actually Zero degrees C) then gives away heat to the surounding air as it expands (by conduction). It then absorbs latent heat from the water to re-equilibrate itself with the ambient temperature. This forces the water to go through a phase change (to ice) but without actually changing temperature at all.
As I said, basic physics. (and horribly over-simplified physics too)
No heat gained and no heat lost overall.
Now imagine the same scenario with a superheated jet of water vapor that is expanding into the atmosphere from a giant geyser.
Using the same principle it is going to cool (slightly) as it expands. How is it going to do this?
By giving up heat to the surrounding air. ie. making it hotter.
There is just no way that you could ever get ice out of this scenario. What you WILL get is steam cooling from 190 degrees to 150 degrees (number just dragged out of thin air at random) and the missing 40 degrees being given up to the surrounding air. If the air had an ambient temperature of 25 degree before, then it will now be at 65 degrees.
Somewhat uncomfortable to breath I would think.
certainly no ice forming anywhere on the planet.