Inflow (meteorology) facts for kids

A supercell thunderstorm with cumulus clouds showing how air flows into the storm.

Inflow is when a fluid, like air or water, flows into a larger area of that same fluid. In weather, inflow usually means warm, moist air moving into a storm system. This air acts like fuel, helping storms grow and become stronger.

What is Inflow?

In simple terms, inflow is the air that gets pulled into a storm. Think of a giant vacuum cleaner sucking in air. Storms, especially big ones like thunderstorms and cyclones, need a constant supply of warm, moist air to keep going. This air brings the energy and water vapor needed for clouds to form and for rain, hail, or even tornadoes to develop.

How Inflow Feeds Storms

The air that flows into a storm usually comes from the lower parts of the atmosphere, close to the ground. This air is often warm and carries a lot of moisture. As this warm, moist air rises into the storm, it cools and the water vapor turns into liquid droplets or ice crystals, forming clouds and releasing energy. This energy helps the storm grow taller and stronger.

Inflow and Different Storms

Inflow is important for many types of storms:

Thunderstorms and Tornadoes

For thunderstorms, especially powerful ones called supercells, inflow is vital. It brings the warm, moist air that helps create the strong updrafts (rising air) within the storm. If a thunderstorm, or a tornado linked to it, stops getting this flow of warm, moist air, it will start to weaken and eventually disappear.

Tropical Cyclones

Tropical cyclones, also known as hurricanes or typhoons, need a huge amount of warm, moist air. This air mostly comes from the warm ocean surface. This constant inflow of energy from the ocean is what allows these storms to become incredibly powerful. Without it, they cannot grow or stay strong.

Extratropical Cyclones

Extratropical cyclones are large weather systems that cause widespread rain and wind. Their inflow is often focused along their cold fronts and warm fronts. These fronts are boundaries where different air masses meet, and the inflow helps to create and strengthen these storm systems.

Related Weather Terms

• Outflow (meteorology): The opposite of inflow, where air flows out of a storm system.

Images for kids

• 

  Airflow in and around a supercell, showing the inflow at the base on the right.

• 

  A weather map of an extratropical cyclone affecting Great Britain and Ireland. The "L" symbol shows the center of the "low," and the different frontal boundaries are marked.