You create a 20-foot-radius, 20-foot-tall cylinder of fog centred on a point within range. The sphere spreads around corners, and its area is heavily obscured. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the radius of the fog increases by 10 feet for each slot level above 1st. When you cast this spell using a spell slot of 6th level or higher, the spell lasts until dispelled, without requiring your concentration.