Snow on the Hallelujah Mountains?
 

This struck me last night, while I was watching a David Attenborough documentry, and now it's really bothering me.

High altitude generally equals snow (not matter the latitude), and no one can argue that the Hallelujah Mountains are pretty high up. But it's warm enough that Trudy runs around in a singlet half the time, and Jake tends to wear just those t-shirts. Not, say, jackets, or huddling around a heater.

Anyone have idea why the mountains aren't covered in snow, even during the night?

Pandora's a tropical environment. Warm year round.

....yes, but that doesn't answer the question. After all, you can ski in Hawaii. It's a question of altitude, not weather.

Pandora's a tiny hothouse, the warm temperatures most likely extend up to that altitude.

Who's to say there isn't a latitude/altitude elsewhere on the planet that has snow? Maybe the plains get snow in the winter?
Also, perhaps we were only there during the 'summer' months? The movie only takes place in a three month period. Who knows what it's like the rest of the year?

It's possible that the mountains aren't that high above sea level, they could be just 2 km above the sea level, which would mean there is no snow when combined with the tropical weather. The Hawaii volcano is something like 5 km right? :)

I'm pretty sure that Pandora's polar caps are covered by snow and ice. As for it snowing up in the Hallelujah Mountains, it might be possible but I don't really know.

For all we know, unobtanium might be warm, melting the snow :P

yeah :P hence the waterfalls that come out of nowhere :D

Ah, no, it's a superconductor :P

I'd guess not a high enough altitude combined with temperature on Pandora. Perhaps it snows on the very highest, just not any seen. The ones shown couldn't be more than a few kilometres at the very most.

... +1 vote for sequal to take place during the winter.... the bioluminesence would look sweet under 2-3 inches of snow...

Snow on hi mountain is not a question of altitude, it's more a question of the thickness of the atmosphere. More the atmosphere is thick more it will need to be hi to have snow.
But it also a question of greenhouse effect, more the atmosphere are able to keep the heat more hi you will need to go to have snow.

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.

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

*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.