Whirlwind

A whirlwind is a vertically oriented rotating column of air formed by instabilities in heating and airflow, and one can last anywhere from a few minutes to a few hours depending on how it forms. Major whirlwinds grow out of supercell thunderstorms, the most intense kind of thunderstorm, when the storm itself begins rotating and interacts with high altitude winds to spin up a funnel that becomes visible once a cloud forms around it. Minor whirlwinds form more simply at ground level, when local winds start rotating near the surface and pick up visible material such as dust or snow as the funnel moves along the ground; because they depend on sustained local wind rather than a storm's energy, they are shorter lived and dissipate when they meet an obstruction such as a building or a stand of trees.