MET - Precipitation

What is precipitation?

• Water that falls from clouds

• Water that contacts earths surface after falling from cloud

• Rain that falls from cloud

• Liquid that contacts earths surface after falling from cloud

What is the Bergeon process?

• water deposits onto ice crystals

• water molecules fuse together through collision

• ice collides with liquid to form a larger ice crystal

• water vapour deposits onto ice crystals

What are the requirements for deposition process?

Select all that apply.

• Part of cloud colder than freezing

• Some turbulence in the cloud to encourage fusion

• Ice crystals and water vapour

• RH <90%

What is the coalescence process?

• Cloud formation through collision of air

• Smaller drops sucked into wake of larger drop

• Ice crystal grows through deposition

• Precipitation created through ice crystals colliding

What are the requirements for the coalescence process?

Select all that apply

• High vertical extent of cloud

• Large condensation nuclei

• Large cloud drops

• Ice crystals

What statement is incorrect?

• Drops or crystals must be heavier than the buoyancy of air to form precipitation

• Coalescence involves a large cloud drop increasing in size

• If clouds don’t have crystals or large liquid drops precipitation is unlikely

• Virga is a form of precipitation

What is virga?

• Water that evaporated before reaching earths surface

• Ice crystal precipitation

• Another name for heavy rain

• Precipitation that falls from CU cloud

Which of the following statements are correct?

• Buoyancy of air must be high to see DZ

• DZ can be from partly evaporated rain drops

• DZ droplets are large and spaced far apart

• DZ is hail that evaporates while falling

What is sleet?

• RA and GR

• DZ and SN

• SN and RA

• GR and SN

What is required for hail formation?

• Strong up and down draughts

• ST cloud

• Cloud below the freezing level

• Snow initially which through coalescence forms hail