Tropic of Capricorn
The Tropic of
Capricorn is an imaginary line of latitude going around the Earth at
approximately 23.5° south of the equator. It is the southernmost point on Earth
where the sun's rays can be directly overhead at local noon. It is also one of
the five major circles of latitude dividing the Earth (the others are the Tropic of Cancer in the northern hemisphere, the equator, the
Arctic Circle and the Antarctic Circle).
The Tropic of Capricorn is significant to understanding the
Earth's geography because it marks the southern boundary of tropics. This is the region that
extends from the equator south to the Tropic of Capricorn and north to the
Tropic of Cancer.
Unlike the Tropic of Cancer, which passes through many areas of
land in the northern hemisphere,
the Tropic of Capricorn passes mainly through water because there is less land
for it to cross in the southern hemisphere.
The Tropic of Capricorn crosses northern Chile and Argentina,
Paraguay, and southern Brazil in South America. In Africa, it crosses Namibia,
Botswana, South Africa, Mozambique and Madagascar. The tropic of Capricorn also
passes through the middle of Australia.
In addition to being used to aid in dividing the Earth into
different parts and marking the southern boundary of the tropics, the Tropic of
Capricorn, like the Tropic of Cancer is also significant to the Earth's amount
of solar insulation and the creation of seasons.
Solar insolation is
the amount of Earth's direct exposure to the sun's rays from incoming solar
radiation. It varies over the Earth's surface based on the amount of direct
sunlight hitting the surface and it is most when it is directly over head at the
subsolar point which migrates annually between the Tropics of Capricorn and
Cancer based on the Earth's axial tilt.
When the subsolar point is at the Tropic of
Capricorn, it is during the December or winter solstice and is when the
southern hemisphere receives the most solar insolation. Thus, it is also when
the southern
hemisphere's summer begins. Furthermore, this is also when the areas
at latitudes higher than the Antarctic Circle receive 24 hours of daylight
because there is more solar radiation to be deflected south due to the Earth's
axial tilt.
Tropical rainforests are found near the equator between the Tropic
of Cancer and the Tropic of Capricorn. Even though they cover only six percent
of the Earth's land surface, tropical rainforests are home to half of the
world's plant and animal species.. Most rainforests in this region are,
therefore, considered tropical. In the tropics there is little change in the
weather throughout the year. It is always hot and there is usually between
1500-4000 millimetres of rain each year.
