Aerosol-Cloud Interactions

Graham Feingold

Clouds come in all shapes and sizes

Cumulus “ominous” Trade Cumulus Warm Continental Cumulus Actinoform Clouds Cumulus Humilis (John Day)

Closed and Open Cells (Garay et al. 2003)

Aerosol Enhances Cloud Brightness

Ship track Images, Aqua, MODIS

Clouds as Generators of Rain

Micron-size drops to mm-sized drops in ~ 20 minutes

10 orders of magnitude change in mass!

Aerosol particles (~ m in size) play a role!

Aerosol Modifies Precipitation• Evidence for suppression in individual warm clouds• Deep convective clouds are more complex

precipitatingNon-precipitating

Small dropsassociated withpollution

Rosenfeld, 2000

Aerosol Suppresses Cloud: The Absorption Effect

Columbia shuttle imageAmazon

smoke

clouds

clouds

Cloud Models

• Demonstrate fundamentals of drop activation and growth in a cloud parcel model

• Discuss results from 3-D models of aerosol-cloud interactions

12 km12 km

Hei

ght,

m