vapour

However, in the model the polar regions of Arrakis have significantly more atmospheric moisture and high cloud cover which acts to warm the climate since water vapour is a greenhouse gas.

Cooling of the atmosphere can also occur, as clouds formed from the emitted water vapour reflect incoming sunlight back to space.

She saw his back for an instant against the pale gloom of the garden, in which vapour was curling.

This shows what a considerable power is lost by cold sides where the vapour is so rare.

As they move in toward the sun long trails of vapour stream back from the somewhat consolidated head.

At other times spouts of green or black vapour rise, mix and lose themselves in the yellow cloud.

The sphere is so near to the sun that if it were possessed of water it would inevitably bear an atmosphere full of vapour.