This action is not available. Life as we know it on the Earth is entirely dependent on the tenuous layer of gas that clings to the surface of the globe, adding about 1% to its diameter a… See more

We commonly think of gas molecules as moving about in a completely random manner, but the Earth’s gravitational field causes downward motions to be very slightly favo… See more

Except for water vapor, whose atmospheric abundance varies from practically zero up to 4%, the fractions of the major atmospheric components N2, O2, and Ar are remark… See more

Ozone is formed by the reaction of O2 with oxygen atoms produced photochemically. As a consequence the abundance of ozone varies with the time of day, the concentrati… See more