The water cycle has no starting point. The sun, heats the water in the oceans and evaporates as vapor into the air. The vapor rises into the air where cooler temperatures cause it to condense into clouds.

Air currents move clouds around the globe, cloud particles collide, grow, and fall out of the sky as rain or snow.

Most precipitation falls back into the oceans or onto land, where, due to gravity, the precipitation flows over the ground enters rivers in valleys in the landscape, with streamflow moving water towards the oceans.

Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge, and some groundwater finds openings in the land surface and emerges as freshwater springs.

Over time, though, all of this water keeps moving, some to reenter the ocean, where the water cycle ends or begins.