Atmospheric moisture processes

Question 1

What are the atmospheric moisture processes?

Answer 1

• evaporation
• condensation
• freezing
• melting
• deposition
• sublimation

Question 2

What is evaporation?

Answer 2

• change of state from liquid to gas (absorbs heat)
• occurs when vapour pressure of a water surface > in atmo.
• sped up by:
  • low initial humidity of air (dry)
  • heat
  • strong winds (air becomes saturated slower)

Question 3

How do you calculate relative humidity?

Answer 3

• actual moisture content x 100 / saturation moisture content at sams T°C pressure

Question 4

What is condensation?

Answer 4

• change of state from gas to liquid
• occurs when T°C reaches/drops below dew point or air mass reaches saturation + requires hygroscopic condensation nuclei
• affected by:
  • radiation cooling
  • contact cooling of air when rested over cold surface
  • adiabatic (expansive) cooling: air rises + expands due to dec. pressure in atmo. Causes T°C drop.

Question 5

What is freezing?

Answer 5

• change of state from liquid to solid
• when T°C falls below 0°C

Question 6

What is melting?

Answer 6

• change of state from solid to liquid above 0°C

Question 7

What is deposition?

Answer 7

• change of state from gas to solid w no intermediate stage
• may deposit on surfaces

Question 8

What is sublimation?

Answer 8

• change of state from solid to gas w no intermediate stage
• might occur in low humidity