PLANETS AND ATMOSPHERES
"You take the blue pill and the story ends. You wake in your bed and you believe whatever you want to believe."
"You take the red pill and
you stay in Wonderland and I'll show you how deep the
rabbit-hole goes."
Vital Climate Graphics :
Introduction to
climate change
Next: Temperature
and CO2 concentration in the atmosphere over the past 400 000 years
1. A planet's climate is decided by its
mass, its distance from the sun and the composition of its atmosphere.
Mars is too small to keep a thick atmosphere. Its atmosphere consists
mainly of carbon dioxide, but the atmosphere is very thin. The
atmosphere of the Earth is a hundred times thicker. Most of Mars'
carbon dioxide is frozen in the ground. Mars' average surface
temperature is about –50°C. Venus has almost the same mass as Earth
but a thicker atmosphere, composed of 96% carbon dioxide. The surface
temperature on Venus is +460°C. Earth’s atmosphere is 78% nitrogen,
21% oxygen, and 1% other gases. Carbon dioxide accounts for just 0.03
- 0.04%. Water vapour, varying in amount from 0 to 2%, carbon dioxide
and some other minor gases present in the atmosphere absorb some of
the thermal radiation leaving the surface and emit radiation from much
higher and colder levels out to space. These radiatively active gases
are known as greenhouse gases because they act as a partial blanket
for the thermal radiation from the surface and enable it to be
substantially warmer than it would otherwise be, analogous to the
effect of a greenhouse. This blanketing is known as the natural
greenhous effect. Without the greenhouse gases, Earth's average
temperature would be roughly –20°C. The climates on Mars and Venus are
very different, but very stable and highly predictable. The Earth’s
climate is unstable and rather unpredictable as compared with that of
the other two planets.
Next: Temperature
and CO2 concentration in the atmosphere over the past 400 000 years
Vital Climate Graphics :
Introduction to
climate change
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