1

Precipitation FormationPrecipitation Formation Cloud droplet – Rain DropCloud droplet – Rain Drop

Homogenous nucleationHomogenous nucleation Super saturationSuper saturation

Heterogenous nucleationHeterogenous nucleation Cloud condensation nucleiCloud condensation nuclei

Aerosols, dust, and pollutionAerosols, dust, and pollution Sea saltSea salt

2

3

4

2 Primary Processes2 Primary Processes Collision and CoalescenceCollision and Coalescence

Adherence and accretion through light Adherence and accretion through light collisioncollision

Froms progressively larger dropletsFroms progressively larger droplets More tropicalMore tropical

BergeronBergeron Saturation vapor pressure (vp) for ice is Saturation vapor pressure (vp) for ice is

lower than saturation vp for waterlower than saturation vp for water Supercooled water and freezing nucleiSupercooled water and freezing nuclei Ice crystal growth through sublimationIce crystal growth through sublimation

5

6

7

8

9

Precipitation SoundingsPrecipitation Soundings(NWS Louisville)(NWS Louisville)

10

Precipitation TypePrecipitation Type fun with fun with precipprecip type type

11

Snow to Liquid RatiosSnow to Liquid Ratios

12

Freezing Rain Freezing Rain DistributionDistribution

(Houston and Changnon)(Houston and Changnon)

13

14

15

16

17