Chapter 7 Precipitation

Question 1

what are the precipitation processes?

Answer 1

1. condensational growth
2. collision-coalescence
3. bergeron (ice crystal) process

Question 2

what is the definition of precipitation?

Answer 2

any form of water that falls from a cloud and reaches the ground

Question 3

what is condensational growth?

Answer 3

more and more condensation occurs = droplet grows

RH>100% because liquid droplets are curved and can hold more water than a flat surface

this is a slow process, will take days before a cloud droplet becomes a rain droplet

Question 4

what is collision and coalescence?

Answer 4

need liquid drops of different sizes, large drops fall faster, they can COLLIDE with smaller drops, they can MERGE

stratus, thin=light drizzle
cumulonimbus=heavy rain

*occurs in warm clouds where T > 0C, all liquid, stratus

Question 5

what increases collision and coalescence?

Answer 5

-range of droplet sizes
-cloud thickness
-updraft in clouds
-charges of droplets and electric field in cloud

Question 6

what is the ice-crystal process?

Answer 6

-cloud consists of ice and super cold water
-ice grows as the liquid water drop shrinks
-due to differences in saturation vapor pressure
*occurs in cold clouds, T < 0C

Question 7

what is homogenous freezing/nucleation?

Answer 7

ice can form w/o CN, ice makes tiny lattice pattern and acts as nucleus

Question 8

what is deposition?

Answer 8

water vapor deposits right onto ice nuclei

Question 9

what is accretion?

Answer 9

ice collides with super cool H2O, causes water to freeze on ice

Question 10

what is aggregation?

Answer 10

ice combines with ice forming a snowflake

Question 11

what are the liquid precipitation types?

Answer 11

drizzle- diameter < .5mm
rain- diameter > .5mm
shower- heavy bursts in between off periods
virga- rain that evaporates before hitting ground

Question 12

what are the frozen precipitation types?

Answer 12

flurries- light-snow falling
snow- frozen H2O
snow squall- heavy, more falls in bursts
fall streaks- snow that evaporates before hitting the ground

Question 13

what is the difference between sleet, feezing rain, and hail?

Answer 13

sleet- refreezes just above ground surface
freezing rain- ground surface is freezing as rain hits, the rain freezes
hail- ice balls that grow due to convection in the clouds

Question 14

how to we measure precipitation?

Answer 14

rain gauge- standard or tipping bucket
weather radar

10 inches of snow will melt down to 1 inch of water