Fog Cloud

CON{c}
You create a 20-foot-radius Sphere of fog centered
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. When you cast this spell using a spell
slot of 2nd level or higher, the radius of the fog
increases by 20 feet for each slot level above 1st.