−10.0
Latitude
Longitude
<
−5.0
−4.0
−3.0
−2.0
−1.0
−0.5
−0.2
0.0
0.2
180
135
90
45
0
−45
−90
−135
−180
−90
−60
−30
0
30
60
90
0.5
1.0
2.0
3.0
4.0
5.0
W m
−2
Aerosol in Global Atmosphere, Fig. 15 Aerosols in the Global AtmosphereGlobal annual mean aerosol surface
radiative forcing from AEROCOM models. (Copyright European Geophysical Union 2006. Reprinted from [76])
altitude
altitude
droplet concentration
effective radius
droplet concentration
effective radius
polluted
clean
N
N
r e
r e
Aerosol in Global Atmosphere, Fig. 16 Illustration of
changes in cloud microphysics resulting from low (clean)
and high (polluted) aerosol fields. Fora cloud with the same
available liquid water content. With more cloud nuclei
available for droplets to form on, the resulting droplets
are necessarily smaller in size. The cloud’s effective radius
is thus smaller and smaller droplets are more efficient
scatters of visible radiation. This, combined with an
increase in the number of scattering droplets, results in a
more reflective cloud. (Courtesy L. Schuller and
J.L. Brenguier)
266
Aerosol in Global Atmosphere