Snow on the Hallelujah Mountains?

[ISV Venture Star]

Pandora has lower gravity (0.8g) than the Earth. This means that the scale height (see link below)

Scale height - Wikipedia, the free encyclopedia

is greater. So you need to be at a higher altitude to see a big change in pressure (and also temperature) than is the case on Earth. Higher values of T would also increase H. OTOH, the Pandoran atmosphere has a fair amount of CO2, and that would mean that the average molecular mass (M) of the atmosphere is higher than on Earth, decreasing H. Hmmm.

[Patrice Maire]

Okay, time for the plant person to step in.
IT's been established that the area where the movie takes place is the equivalent of a tropical jungle. What we saw in other areas (the plains and the coast) the plant diversity is very wide.
The plants on top of the floating mountains is different than the plants growing on the planet itself. There are likely micro climates on each individual floating rock as well and due to their floating and rotating, the climate changes constantly as well.
The flora at Site 26 seems to bear out a different weather pattern than on the ground. Long grass, different plant varieties that seem to indicate possible colder weather tolerance.
So, we'll have to see what Cameron plans for us in the next movie and perhaps in the novel as well.

[Ashen Key]

Originally Posted by Patrice Maire

So, we'll have to see what Cameron plans for us in the next movie and perhaps in the novel as well.

*wry* Unfortunately, I role-play pre-canon Trudy in a multifandom game, and I can't really go 'sorry, guys, have to wait four years for the answer on that one!'

But you make an excellent point re: the plants being different at Site 26 than in the jungle - I hadn't noticed that before.

[Sìltsan'awpo]

Isn't there a lot of mist around the mountains? Maybe the atmosphere is thin and it's easier for the sunlight to go throught it (or it's thicker and it's harder for sunlight to leave) and it evaporates water before it turns into snow?

Lol, I really don't know xD Just my $0.02

[Banefull]

We had this exact same post on A-F. Thought I'd post what I came up with there on here also:

"Snow does not probrably exist on the mountains for a combination of reasons. First off, since this is a jungle, the air is full of moisture and water retains heat very well and releases it slowly, keeping the temperature rather constant (even at night). Next, a lot of foilage grows on the floating rocks which helps to absorb even more heat. Finally the atmosphere is very thick with clouds preventing a lot of heat from radiating into back into space. In the the scene where the valkyrie shuttle enters orbit we can clearly see some very very thick cloud formations blanketing the entire atmosphere as far as the eye can see. We also see lots of mist and cloud cover around the mountains themselves (remember Norm's comment that they cannot see anything after going VFR). All this = no snow.

Something that occurred to me was that Pandora orbits a giant gas giant. If I remember correctly, it enters into a dark phase for quite a while as it passes through the shadow of Polyphemus. Perhaps in the middle of this period we could see snow and ice formations at higher elevations. All depends on how well the environment can retain heat. Would be an interesting thing to know. I could easily imagine that during this time all the Ikrans would migrate away from their nests at the top of these mountains to the jungle canopy."

[Patrice Maire]

I just read through my Survivalist guide for the first time and there are polar ice caps but another reason for no snow on the Thundering Rocks could also be the magnetic fields and their constant movement.
So, now that we've flogged this topic entirely to a squishy pulp on the ground....

[Human No More]

The magnetic fields would do nothing on their own... Movement COULD, I guess, but most remain in place.

[Banefull]

Magnetism does have some effects on water like reduced surface tension and it can cause snow to stick less to other surfaces in certain conditions but like human no more said above me, theres no real effect significant effect on snow formation.