ESS101C
Prof.
Jin-Yi Yu
Seasons and the Size of Ice Sheet
qContinental ice sheets exist because the overall
rate at which snow and ice accumulates equals or exceeds the overall rate
of ice loss or ablation.
qIt is the summer
insolation that determines the ice
sheets grow and shrink.
qLow (cold) summer
insolation is the critical factor that cools the climate enough to
allow snow and ice to persist from one winter to the next.
qWinter insolation
is not important to ice sheet sizes, because (1) the temperatures are
always cold in winter and (2) the Sun at high latitudes are low in the
sky, regardless of ongoing orbital changes.