Environmental Science
The aurora is produced by:

Reflections of sunlight by polar ice fields
Burning oxygen caused by the intense sunlight at high altitude
The combination of molecular and atomic oxygen to form ozone
Fast-moving charged particles colliding with air molecules
Scattering of sunlight in the upper atmosphere

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Environmental Science
Much of Tibet lies at altitudes over 18,000 feet where the pressure is about 500 mb. At such altitudes, the Tibetans are above roughly:

50% of the air molecules in the atmosphere
10% of the air molecules in the atmosphere
25% of the air molecules in the atmosphere
75% of the air molecules in the atmosphere

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