1. Making a snow and Inflating a bicycle tire (chapter.6)
By Group No:1
Wisawa M
Santi P
Nuthapat S
Antonio L

2. What is snow?
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.

3. Two of the Most Important Variables in Making Snow
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

4. How does it work?
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.

5. The Science of Snow Making

6. Heat Exchange Process 
Snow making is a heat exchange process. Heat is removed from snowmaking water by evaporative and convective cooling and released into the surrounding environment.

7. Wet Bulb Temperature 
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.

8. Nucleation Temperature
 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. 

9. Liquid form
Solid form
(hexagonal array)

10. Inflating Bicycle Tire

11. INTRODUCTION
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

12. WHY DOES THE BICYCLE TIRE GET HOT WHEN INFLATED?
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

13. 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

14. Adiabatic 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

15. 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