Dust devils form when hot air at the surface begins to rise rapidly with much cooler air above it and higher up into the atmosphere. The hot air then stretches and causes a spinning motion much like a tornado. Dust devils form in an upward motion from the ground to the sky. They are short-lived whirlwinds because cold air eventually gets pulled in. Dust devils can become tornadoes when a storm's updraft moves over the the existing ground circulation. The updraft from the storm can draw the dust devil vertically into the base of the cloud, often strengthening the rotation.
For dust devils to form, you usually need plenty of sunshine, little to no wind, and a very cool atmosphere above. Dust devils can just be a few feet wide and high, to much bigger. Wind speeds can be up to 60 mph. They can cause damage. I saw that when I lived in New Mexico.
Dust devils become visible when they form over barren terrain and desert-like terrain.
Dust devils are usually harmless, but can on rare occasions grow large enough to pose a threat to both people and property. They are comparable to tornadoes in that both are a weather phenomenon involving a vertically oriented rotating column of wind.