AtmosphereEdit

Pandora's atmosphere is a mixture of nitrogen, oxygen, carbon dioxide (>18%), xenon (>5.5%), methane, and hydrogen sulfide (>1%) and is about 20% denser than the atmosphere on Earth primarily due to the high percentage of Xenon; a heavy, colorless, odorless, and generally unreactive noble gas. The high concentration of carbon dioxide in the Pandoran atmosphere makes it extremely poisonous to humans, rendering them unconscious in about 20 seconds and causing death in about 4 minutes. The hydrogen sulfide present is also quite poisonous; concentrations over 1000 ppm (0.1 %) can cause immediate collapse with subsequent loss of breathing, even after inhalation of a single breath.

The increased air resistance within this denser atmosphere has a number of effects:

Lower terminal velocity. Combined with Pandora's twenty-percent lower gravity, a freely falling object's maximum speed is significantly less than on earth. A Na'vi who happens to fall from a flying mountain banshee has a good chance of surviving uninjured if they are over a forested area. Even over water, falling spread-eagled can reduce their speed sufficiently to allow an impact with the surface that will not knock them unconscious.

The increased mass of the denser air means that more force is required to accelerate it as it is moved out of the path of a moving object. Humans on Pandora experience this when they try to run – it feels like there is a wind blowing against them, even though the air is still. They are further hampered by the fact that the reduced gravity causes their boots to slip more readily on paved or smooth surfaces, giving them less traction to force their bodies forward. The Na'vi compensate for this loss of frictional force by curling their large toes into the soft ground, and Pandoran six-legged animals use their many feet to gain a purchase on protruding rocks or small crevices.

Flying animals can take advantage of both the lower gravity, which reduces the weight of their body, and the increased air density, which requires more force to displace with the downward/rearward stroke of their wings, and thus gives the animals body more impetus with each flap. The downside is that the denser air is harder to move through, and requires highly-efficient streamlining to achieve high flight speeds.

Plants are subject to greater wind force, as the greater air density means that the moving air carries more kinetic energy and more momentum, and the plants, leaves, stems, branches, and trunks must all have a greater strength and/or flexibility to resist it.

Annons

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March 2015