The fur on the arctic polar bear appears white all year. The color of the fur is an example of:

The color of the fur is an example of "phenotype".

Explanation:

All the measurable features of an entity arising from the relationship of complete genetic descent of the genotype with the atmosphere, is understood as phenotype. This  include conduct, biochemical traits, colour, shape and size. Thus white fur in polar bear helps them to camouflage their surroundings i.e arctic climate. Basically the polar bear skin is balck color but fur covering their skin are yellow as there is no white pigment on the coat of the polar bear. Their body fat helps them to keep warm while swimming also and double layered fur insulate them.

well first you need the sample of the temperature and gas level. i couldnt write a hypothesis unless i had some data. i think temperature changes will effect volumes of gas because gas changed into a solid or liquid at specific temperatures.