Types of Precipitation

Question 1

What are the diff. types of pptn?

Answer 1

• clouds
• rain
• hail
• snow
• dew
• fog

Question 2

How do clouds form?

Answer 2

• air rises + cools [adiabatic cooling] - humidity
• humidity inc to 100% + saturation occurs
• air warmer than surrounding air continues to rise, creating tall (thunder) clouds: unstable
• formed of Ms of tiny water droplets held in suspension

Question 3

What are the diff types of clouds?

Answer 3

• cirrus: wispy + high
  
  • mostly consists of ice crystals
  • inc. cirrocumulus + cirrostratus
• alto: middle-height
  
  • consists of water drops + exists at T°C < 0°C
• stratus: layered
  
  • dense, grey + low lying
  • inc. stratocumulus
• nimbus: rain (water bearing)
  
  • inc nimbostratus
• cumulus: heaped + flat-bottomed

Question 4

What is rain?

Answer 4

• liquid water droplets heavy enough to fall to ground
  
  • between 0.5-5mm
• drizzle: rainfall < 0.5mm
• varies in amount, intensity + duration

Question 5

What is hail?

Answer 5

• concentric rings of clear + opaque ice
• raindrops freeze inside a cumulonimbus cloud
• hailstones then collide w supercooled water, freezing on impact
• rising + falling in cloud causes repeated melting + freezing until hailstone heavy enough to fall

Question 6

What is snow?

Answer 6

• frozen pptn
• forms when T°C is below freezing + water vapour turns solid
• heaviest snowfall: when warm moist air is forced to rise in orthographic or frontal rainfall, as v. cold air contains limited moisture

Question 7

What is dew?

Answer 7

• direct deposition of water on a surface
• occurs in anticyclonic systems w rapid radiation cooling at night
• T°C reaches dew point, + condensation/direct ground/veg. pptn occurs

Question 8

What is fog?

Answer 8

• cloud at ground lvl + results from radiation cooling
• common over sea in autumn + spring bc contrast in T°C between land + sea is sig.
• steam fog: localised when cold air blows over warmer water + air becomes saturated due to evaporation, resulting condensation causes steam
• advection fog:
• formed when winds move towards pole over cold sea, so chilled below due point
• forms over cold ocean current, the wind blows over