Transcript Making a snow and Inflating a

By Group No:1
Wisawa M. 5435121
Santi P. 5516847
Nuthapat S. 5532013
Antonio L. 5538435
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Snow cover is a part of the cryosphere, which traces
its origins to the Greek word kryos for frost. Snow is
precipitation in the form of ice crystals. It originates in
clouds when temperatures are below the freezing
point (0 degrees Celsius, or 32 degrees Fahrenheit),
when water vapor in the atmosphere condenses
directly into ice without going through the liquid stage.
Once an ice crystal has formed, it absorbs and
freezes additional water vapor from the surrounding
air, growing into a snow crystal or snow pellet, which
then falls to Earth.
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Temperature and Humidity; Both of them must be
low enough for snowmaking.
Water Temperature; Water must be colder than
the outside. Ex. Outside 9 C, water must be lower
than -1 C
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Ambient Temperature; outside must be cold at
least freezing point
Evaporation; The second factor is heat loss
through evaporation.
Surface Area
The third way we cool the water is by increasing
the surface area of the drop.
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Snow making is a heat exchange process. Heat is
removed from snowmaking water by evaporative
and convective cooling and released into the
surrounding environment.
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The temperature of a water droplet exiting a snow
gun is typically between 1 C and 6 C. Once a
water droplet passes the nozzle and is released
into the air, its temperature falls rapidly due to
expansive and convective cooling and evaporative
effects.
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Once the wet bulb temperature is know, there
must be a way to predict whether water droplets
will actually freeze at that temperature. Ice is the
result of a liquid (water) becoming a solid (ice) by
an event called nucleation. A water droplet must
first reach its nucleation temperature to freeze.
Liquid form
Solid form
(hexagonal array)
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Thermodynamics is the scientific study of the
interconversion of heat and other kinds of energy
When a tire is full of air, it is said to be inflated.
When a tire has less air in it then it needs to
operate it is said to be deflated.
U = q + w
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U = q + w
Work is done to the gas in the tire, so the value of
w is positive and q = 0
The increase of w leads to the increase of 
w increase = temperature increase
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If the gas is thermally isolated from the surroundings,
then the process is said to occur adiabatically
(adiabatic change)
First Law becomes ΔU = 0 + w
Interaction form between particles with the concurrent
release of energy
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Adiabatic is the change of energy
When a gas expands, it does work on the
surroundings
compression of a gas to a smaller volume similarly
requires that the surroundings perform work on
the gas
In an adiabatic change, q = 0, so the First Law
becomes ΔU = 0 + w
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Since the temperature of the gas changes with its
internal energy
it follows that adiabatic compression of a gas will
cause it to warm up
adiabatic expansion will result in cooling