Rain & Snow

Follow a water molecule from vapor to rain, snow, ice, or hail.

About Rain & Snow

Precipitation begins when cloud droplets or ice crystals grow large enough to fall. Temperature and humidity through the atmosphere determine whether they remain snow, melt into rain, refreeze into sleet, or freeze on contact at the surface.

Visual learning: These pages use real Wikimedia Commons and scientific weather imagery. Final image URLs should be browser-tested before deployment.

Thunderstorm — ThunderstormThunderstorms form when warm moist air rises into an unstable atmosphere.

Tornado — TornadoTornadoes are rapidly rotating columns of air connected to thunderstorms.

Hurricane — HurricaneTropical cyclones are organized rotating storm systems fueled by warm ocean water.

Snowstorm — SnowstormWinter storms can combine snow, wind, cold, and low visibility.

Rain

Rain forms from liquid droplets or melted ice particles.

Snow

Snowflakes grow as ice crystals in cold clouds.

Sleet

Sleet is made of ice pellets.

Freezing Rain

Freezing rain is liquid when it falls but freezes on cold surfaces.

Hail

Hail grows inside strong thunderstorm updrafts.

Snowflake Shape

Snow crystals often show sixfold symmetry.

Measuring Precipitation

Rain gauges measure liquid precipitation.

Water Cycle

Precipitation is part of the global water cycle.

Rain

Warm clouds can grow raindrops through collision and coalescence, while many midlatitude storms begin with ice crystals aloft.

Snow

Temperature and humidity influence crystal shapes.

Sleet

Snow melts in a warm layer, then refreezes before reaching the surface.

Freezing Rain

It can coat roads, trees, and power lines with dangerous ice.

Hail

Ice stones can make repeated trips through supercooled water before becoming too heavy for the updraft.

Snowflake Shape

The molecular structure of ice gives snowflakes their hexagonal pattern.

Measuring Precipitation

Snow is measured by depth and by how much liquid water it contains when melted.

Water Cycle

Water evaporates, condenses, falls, infiltrates soil, flows through rivers, freezes, melts, and returns to the ocean and atmosphere.