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| q |
Continental ice sheets exist because the overall rate at
which snow and
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ice accumulates equals or exceeds the overall rate of ice loss or
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ablation.
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| q |
It is the summer insolation
that determines the ice sheets grow and
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shrink.
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| q |
Low (cold) summer insolation is the critical factor that cools the
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climate enough to allow snow and ice to persist from one
winter to the
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next.
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| q |
Winter insolation is not important to ice sheet sizes, because (1)
the
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temperatures are always cold in winter and (2) the Sun
at high latitudes
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are low in the sky, regardless of ongoing orbital changes.
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