Venus

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Venus
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Physical Properties of the Earth and Venus
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The Venusian Day, the Venusian Year, and Venusian
Jet Streams
Venus rotates westward with a sidereal period of
243.01 days and revolves eastward around the sun
with a sidereal period of 224.68 days.
Its synodic rotation period is 116.74 days, so
regions near the equator have 58 days of sunlight
alternating with 58 days of darkness.
The hottest part of the planet is around the
subsolar point
The hot air from the subsolar point rises and
drifts toward the night side of the planet and
the poles.
This produces westward, high-speed (200 300
km/h) winds in the upper atmosphere.
Why do these winds blow toward the west?
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Ultraviolet Image of Venus
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Venus Atmosphere
96 CO2, 3.5 nitrogen, 0.5 other (H2O, sulfuric
acid, hydrochloric acid, hydrofluoric acid).
Atmospheric pressure at surface 92 times
surface atmospheric pressure on Earth.
Although wind speeds are about 300 km/h in the
upper levels, they decrease below the clouds to
less than 5 km/h near the ground. Why?
Why is Venus atmosphere so different from
Earths?
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Radar Map of Venus
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Soviet Venera Image of Venus Surface
Venus rocks and soil are actually dark gray. Why
do they look orange in the Venera photographs?
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Earth Topographical Map
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Topographical Map of Venus
Most of the planets surface consists of low
plains.
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Pancake Domes
Pancake domes are the result of volcanic
eruptions of viscous lava.
250 km
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Aine Corona with Pancake Domes
A corona is a large bulge in Venus surface due
to the pressure of magma below the crust.
300 km
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Arachnoids
An arachnoid is a network of lava-filled cracks
in Venus crust. The cracks are caused by magma
pressure, and their name is due to their
resemblance to spider webs.
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Impact Crater
Why isnt it symmetrical?
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How much more intense is sunlight at Venus than
it is at Earth?
However, 76 of the light that hits Venus upper
cloud layers is reflected, and only about 2.5
actually reaches the ground.
In that case, why is its surface temperature so
high?
Greenhouse effect incident sunlight is absorbed
by the ground, the warm ground emits infrared
radiation, the CO2 atmosphere is opaque to
infrared radiation.
Because of the trapped IR, the temperature of the
air increases until the rate of emission of IR by
the air is equal to the rate of emission by the
ground.