Chapter 13: Precipitation (PP ch 13)

Question 1

Precipitation theories (2)

Answer 1

Bergeron Process

Coalescence Theory

Question 2

Bergeron Process

Answer 2

Clouds at < 0 C

ice crystals attach to SCWD

Question 3

Coalescence Theory

Answer 3

Water droplets .02 mm combine and fall

Question 4

Precipitation types (10)

Answer 4

DZ - Drizzle
RA - Rain
Virga
IC - Ice Crystals
SN - Snow
SG - Snow Grains
Snow Pellets
GS - Small Hail
PL - Ice Pellets
GR - Hail

Question 5

DZ

Answer 5

Drizzle
Stratiform clouds
< .5 mm
V = 4 m/s

Question 6

RA

Answer 6

Rain
Cumuliform / stratiform clouds
.5 mm < diam < 5.5 mm
V = 9 m/s

Question 7

IC, SN, SG, SP, GS, PL, GR

Answer 7

Ice crystals - stratus, small
Snow: 4 to -5C, largest flakes at 0
Snow Grains - opaque grains < 1 mm
Snow Pellets - conical, break on ground, 2 - 5 mm
Small Hail - thicker coating, < 5 mm
Ice Pellets - clear, conical, bounce, frozen water droplets
Hail - 5 - 50 mm, Cb, 1 kg max

Question 8

Precipitation Continuity

Answer 8

Continuous - 60 min no breaks (As, Ns)
Intermitent (As, Sc)
Showers (Cu, Cb)

Question 9

Precipitation Intensity

Answer 9

Light
Moderate
Heavy

Question 10

Visibility (5)

Answer 10

Moderate rain: 3 - 10 km
Heavy rain: < 1 km
Moderate snow: < 1 km
Drizzle: < 500 m
Heavy snow: < 50 m

Blown surface snow worsens visibility

Question 11

METAR

TEMPO, Ceiling, Cloud Base

Answer 11

Tempo - can happen in time range, lasts < 1 h
Ceiling - lowest of 4+ oktas value (BKN, OVC)
Cloud base - lowest clouds