Snowing on Mars

[Orleander]

If its snowing on Mars, doesn't that mean there is water in the atmosphere? Can there be water in the atmosphere without water being on the planet itself?

In a Mars exploration (http://www.popsci.com/military-aviation-amp-space/article/2008-10/its-snowing-mars) milestone, a laser remote sensing instrument on the Phoenix Mars lander has detected snow falling on the red planet. Data from the light detection and ranging (lidar) instrument—designed to gather information about interactions between the Martian atmosphere and ground surface—showed the snow falling from clouds about 4 kilometers (2.5 miles) above the spacecraft's landing site....

[snake river rufus]

Yes and yes. Have they determined if the snow is H2O?

[OilIsMastery]

If its snowing on Mars, doesn't that mean there is water in the atmosphere?
Depends on what you mean by water. If you mean solid water then yes. If you mean liquid water then no.

Can there be water in the atmosphere without water being on the planet itself?
No. The atmosphere is a part of the planet.

http://www.sciforums.com/showthread.php?t=86059

Have they determined if the snow is H2O?
:crazy:

Who is they? If it's a group you're part of then obviously not.

[Orleander]

....No. The atmosphere is a part of the planet....

Ugh, a hairsplitter.

Fine! Can there be water in the atmosphere without water being on the dirt of Mars?

[OilIsMastery]

Can there be water in the atmosphere without water being on the dirt of Mars?
I don't know how that would be possible but even if it is possible it doesn't matter on Mars because they've already found snow on the dirt.

http://www.calacademy.org/exhibits/xtremelife/images/mars_ice_crater.jpg

http://discovermagazine.com/2006/jun/cover/polarcap.jpg

[snake river rufus]

.
Who is they? If it's a group you're part of then obviously not.

"They" would be the scientists looking at the data. That should be obvious.
:crazy: yourself

[Orleander]

OK,
If there is water in the atmosphere, does that mean there is liquid water (not frozen) on the dirt of Mars?

[Orleander]

I don't know how that would be possible but even if it is possible it doesn't matter on Mars because they've already found snow on the dirt.....

why doesn't it matter?

[OilIsMastery]

If there is water in the atmosphere, does that mean there is liquid water (not frozen) on the dirt of Mars?
They are looking: http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20080731.html

http://news.nationalgeographic.com/news/2006/12/061206-mars-water.html

[Orleander]

If its too cold, how does it get into the atmosphere?

[OilIsMastery]

If its too cold, how does it get into the atmosphere?
Good question. Apparently it's not too cold...:D

[Orleander]

You changed your post. (#9). I should have quoted you.

You said it was too cold, now its not too cold.
If its not too cold, then there is liquid water on the dirt of Mars. right?

[OilIsMastery]

Right: http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20080731.html

[D H]

If its too cold, how does it get into the atmosphere?
Sublimation. Leave an ice cube in your freezer for a couple of weeks. It will shrink markedly.

[Orleander]

would it do that even if I never ever opened the freezer again to check? If I never let in warm air, it would still shrink?

[D H]

would it do that even if I never ever opened the freezer again to check? If I never let in warm air, it would still shrink?
The warm air is not what makes the ice cube shrink. Solids can transition directly to gases via sublimation (http://en.wikipedia.org/wiki/Sublimation_(chemistry)).

Here is a phase diagram of water:
http://boomeria.org/chemlectures/textass2/fig17-9.jpg

Three curves emanate from the triple point.
The solid-liquid line is nearly vertical, but angles up slightly to the left from the triple point. (This is highly anomalous. The solid-liquid line angles slightly to the right in almost all substances but water. One consequence of this is that ice water is less dense than liquid water; ice floats. In most substances the solid form will sink rather than float.)
The liquid-vapor line curves up and to the right from the triple point.
The solid-vapor line curves down and to the left from the triple point.

Our everyday world is represented by the horizontal line at 101.3 kPa, or one atmosphere of pressure. Along that line, solid water melts at 0o Celsius and liquid water boils at 100o Celsius. The reverse processes occur when going from right to left. Water vapor condenses into liquid water, which in turn freezes to form ice. A substance can cross the solid-vapor line as well as the solid-liquid and liquid-vapor line. Going directly from solid to vapor is called sublimation; going from vapor to solid is called deposition.

A frost-free freezer works in part by keeping the air in the freezer extremely dry -- dry enough to make the water vapor partial pressure be below the triple point pressure. Ice cubes in such a freezer will sublimate.

The total pressure on Mars is about 0.6 kPa -- right around the triple point pressure of water. The water vapor partial pressure is much lower than the triple point pressure on Mars. Water ice will easily sublimate into water vapor on Mars.