Question

How can pollution occur at each point in the water cycle

Answer 1

Answer:

The atmosphere is the superhighway in the sky that moves water everywhere over the Earth. Water at the Earth's surface evaporates into water vapor which rises up into the sky to become part of a cloud which will float off with the winds, eventually releasing water back to Earth as precipitation.

Note: This section of the Water Science School discusses the Earth's "natural" water cycle without human interference.