We call the poles of the earth to the circles of
land situated at the north and the south of the
globe. The Artic Circle including the north pole
and the Antartic Circle including the south pole.
Midway between the poles of the earth is the
equator, an imaginary line that circles the globe
all around. The earth spins about its axis which
includes the north and south poles, but it bulges
to its greatest extent at the equator.
refer to climate as the simply weather averaged
over a time period of one year or more. At the
earths poles the climate is termed polar, and at
the equator it is termed tropical. Each of these
climate zones is characterized by a distinctive
temperature range, rainfall amount, and type of
vegetation.At the poles the number of days without
sunset, and days without sunrise is maximum.
Considering the low sun angles at each pole, the
solar gain is minimal so winters are long and
quite severe, while summers are mild and brief.
The soil near the poles thaws for just a short
time each year at the surface, beneath this the
ground is permanently frozen (permafrost). This of
course limits root growth and, ultimately, plant
size. Plants that can survive hard frosts or
freezes are called Hardy Plants. These plants can
handle varying levels and durations of freezing,
explaining their distributions up into the high
latitudes toward the Polar Circles. Where
permafrost exists the thin layer of soil that
thaws briefly in summer supports the distinct
vegetation known as "tundra". These are among the
toughest plants on earth. They go through their
life cycle in just a few weeks of summer and then
tolerate extreme cold for the rest of the year.
They tend to be short in stature.
equator, there are the tropical plants. These
plants generally cannot survive winters, and so
are restricted to their homelands. Among the
popular plants that we can find at the equator are
the mango and the banana trees.
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