CFI Pop Quiz #318 - Driving Force

[Chris Burgess]

Which is the primary driving force of weather on the Earth?

A) The Sun.
B) Coriolis.
C) Rotation of the Earth.

[Ga6riel]

im completely out of my depth here, ~ going with A

[GyroRon]

A...............................

[Paul_Zurawski]

Going with (a)

[Papa Smurf]

I say... C

[birdy]

I'll cover all possabilitys and say ' mum nature'.

[JByrd]

A.... No sun no wx. Lots of water ice in a hurry. In a month the atmospheric gasses would freeze too.

Jim B.

[Al_Hammer]

JByrd,

Atmosphere freeze in a month? I'm curious how you obtained that figure.

The following opinions indicate a period of years or decades for the atmosphere to freeze (and the oceans would probably never freeze completely.)


Dear sci.physics.research,

Perhaps you could resolve a short-running discussion in another
newsgroup.

How long would it take for the oceans, and then the atmospere to freeze
if the sun were suddenly removed?
===========================
Heat loss from the earth is, on average, the same as its gain from the
sun radiation, gravitational distortion due to moon and sun, and
radioactive activity. The first is a surface thing, the others are
internal.

Each year, the Earth points its poles firmly away from the sun and
towards the bleak coldness of space, In Antarctica, the Weddel sea, a
vast area, freezes. The ice advances some 10 degrees of latitude in
under 6 months. If, in the absence of sun, this rate of advance
continues, the remaining 70 or so degrees to the equator would be
covered in another 3.5 years. However, the Weddell sea is not the open
ocean, so I guess the ocean surface freezing would take longer, up to 10
years, say.

Once the ocean's heat was capped by ice, the atmosphere would lose heat
unchecked.

In Siberia, the air temperatures, untempered by oceanic influences, drop
from, say +17C (290K) to -33C (240K) in the winter season. Now if the
drop is proportional to the temperature difference between air and space
(less than 10K), the temperature would drop by 1/6 every 6 months, or
30% a year. It would be down to 120K 2.5 years after the sun went, 85K
after 3.5 yrs and 65K after 5 yrs.

Oxygen liquefies at approx 95K and Nitrogen freezes at 65K.

So my answer to atmosphere freezing is:

Not less than 5 years, probably not more than 20 years.

============

> How long would it take for the oceans, and then the atmospere to freeze
> if the sun were suddenly removed?

That's easy: never.
Since water is densest above freezing,
and since there is a steady heat flow
outwards from the earth' core
the oceans will not freeze solid.

The thickness of the ice layer
will be determined by the balance of the heat flows,
http://www.lns.cornell.edu/spr/2003-01/msg0047519.html
=========

Different parts of the Earth would freeze at different rates if the Sun were to suddenly go out. We can guess some of the rates just from considering what happens at night. Over the course of 12 hours without sunlight, temperatures tend to drop between 10 and 30 degrees Fahrenheit, depending on whether you're in a desert or near the ocean. So you might expect that things would start to freeze in only two or three days with no Sun. The ocean acts like a big reservoir of heat, since its layers can mix and bring warm material easily to the surface. Areas near the ocean would remain warmer for a while longer, but the freezing would probably start in only a few months. After the time of an arctic winter, the ocean would be filled with pack ice. Since the pack ice of the arctic ocean averages about a dozen feet thick during the winter, one might guess the oceans would freeze at about the rate of a 50 feet a year. This rate would slow as a thick blanket of insulating ice was accumulated, but the effect would be the same, the warm water would be so far down as to be useless to people on the surface unlucky enough to be looking for it. Eventually, the atmosphere would liquefy and then freeze. That would probably take a few decades to begin.

http://www.science.ca/askascientist/viewquestion.php?qID=383


===========
The interior of Earth reaches temperatures of 5650 +/- 600 kelvins. The planet's internal heat was originally generated during its accretion, and since then additional heat has continued to be generated by the decay of radioactive elements such as uranium, thorium, and potassium. The heat flow from the interior to the surface is only 1/20,000 as great as the energy received from the Sun.

====
Earth is actually beyond the outer edge of the orbits which would be warm enough to form liquid water. Without some form of a greenhouse effect, Earth's water would freeze. Paleontological evidence indicates that at one point after blue-green bacteria (Cyanobacteria) had colonized the oceans, the greenhouse effect failed, and Earth's oceans may have completely frozen over for 10 to 100 million years in what is called a snowball Earth event.

[Chris Burgess]

Some education we're getting here boys and girls.

The most correct answer is "A". Which is the primary driving force of weather on the Earth? (A) The Sun. Reference AC 00-6A, Chapter 1