On this planet.
If not what are the most important factors that tilt the balance?

On Mar 25, 11:58*pm, "Lawrence Jenkins" wrote:
On this planet.
If not what are the most important factors that tilt the balance?

Clouds!

Cheers, Alastair.

In message , Lawrence
Jenkins writes
On this planet.
If not what are the most important factors that tilt the balance?

You haven't defined your terms sufficiently. But if one were to define
energy in as solar radiation at the top of the atmosphere (I understand
that other astronomical sources are sufficiently small that they can be
neglected) then energy in is obviously not constant. There is an annual
variation due to the eccentricity of the Earth's orbit, and longer
period variations due to variability in the solar output, and changes in
the Earth's orbit.

If you were to define energy in as the energy absorbed at the Earth's
surface, albedo variations become important, as does the axial tilt
(only the proportion of the radiation that hits Antarctica can be
reflected off the Antarctic ice sheets).

Or did you mean to ask whether energy in and energy out are always
equal. That is clearly not the case locally (the hottest and coldest
periods are on average significantly later than the solstices). I
suspect that even if the climate was in equilibrium that would not be
true globally, but there would be annual oscillations, and interannual
variability, in the heat balance. As the climate is not in equilibrium,
some of the incoming energy is going into warming the oceans, so energy
in may be greater than energy out (there's also the matter of ice sheet
balance, but in the absence of knowledge of the magnitude of snowfall
increases in Antarctica I can't be sure whether this is an energy sink
or an energy source.)
--
Stewart Robert Hinsley

"Lawrence Jenkins" wrote in message
...
On this planet.
If not what are the most important factors that tilt the balance?
No.
Water, in all it's forms.
Alex.

On Fri, 26 Mar 2010, Alex Stephens Jr wrote
"Lawrence Jenkins" wrote in message
.. .
On this planet.
If not what are the most important factors that tilt the balance?
No.
Water, in all it's forms.

Which reminds me of a question I've long wanted to ask but been afraid
it was unanswerable or just daft. Does the quantity of water in and on
and round the planet remain the same, though in varying forms? Or do
some water molecules become irrevocably split, and others form newly
from handy bits of hydrgen and oxygen?



--
Kate B

PS 'elvira' is spamtrapped - please reply to 'elviraspam' at cockaigne dot org dot uk if you
want to reply personally

In message , Kate Brown
writes
On Fri, 26 Mar 2010, Alex Stephens Jr wrote
"Lawrence Jenkins" wrote in message
. ..
On this planet.
If not what are the most important factors that tilt the balance?
No.
Water, in all it's forms.

Which reminds me of a question I've long wanted to ask but been afraid
it was unanswerable or just daft. Does the quantity of water in and on
and round the planet remain the same, though in varying forms? Or do
some water molecules become irrevocably split, and others form newly
from handy bits of hydrgen and oxygen?

Water molecules can be created (e.g. by burning organic material) and
destroyed (e.g. photosynthesis). This is a cycle, and over the course of
a year the amount of water in the system averages out to roughly
constant.

Water molecules can be split by UV radiation in the upper atmosphere
(photodissociation) and the resulting hydrogen lost to space (because
the velocity of hydrogen atoms at exospheric temperatures is comparable
to the escape velocity. This leads to a reduction in the amount of water
on the earth, but because of the "cold trap" there's not much water in
the upper atmosphere, and consequently this is a slow process. But in
the case of Venus, the planet has lost most of its water in this manner.
--
Stewart Robert Hinsley

On Fri, 26 Mar 2010, Stewart Robert Hinsley wrote
In message , Kate Brown
writes
On Fri, 26 Mar 2010, Alex Stephens Jr wrote
"Lawrence Jenkins" wrote in message
...
On this planet.
If not what are the most important factors that tilt the balance?
No.
Water, in all it's forms.

Which reminds me of a question I've long wanted to ask but been afraid
it was unanswerable or just daft. Does the quantity of water in and
on and round the planet remain the same, though in varying forms? Or
some water molecules become irrevocably split, and others form newly
from handy bits of hydrgen and oxygen?

Water molecules can be created (e.g. by burning organic material) and
destroyed (e.g. photosynthesis). This is a cycle, and over the course
of a year the amount of water in the system averages out to roughly
constant.

Water molecules can be split by UV radiation in the upper atmosphere
(photodissociation) and the resulting hydrogen lost to space (because
the velocity of hydrogen atoms at exospheric temperatures is comparable
to the escape velocity. This leads to a reduction in the amount of
water on the earth, but because of the "cold trap" there's not much
water in the upper atmosphere, and consequently this is a slow process.
But in the case of Venus, the planet has lost most of its water in this
manner.


wow. You learn something new every day. Thank you, Stewart.

--
Kate B

PS 'elvira' is spamtrapped - please reply to 'elviraspam' at cockaigne dot org dot uk if you
want to reply personally