Dust devils, whirlwinds or Willy Willys

A dust devil is a whirlwind of air into which dust and debris (or hay see below) gets caught up, making it visible. So, there will be plenty more of them going on, but they just won't be seen. They need dry, often sunny conditions, with strong heating of the land and light-ish surface winds. Usually, but not always, a summer phenomenon here in the UK.   They are not formed in the same way as tornadoes, they are just intense thermals of hot air rising. Rotation of the air along the ground gets kicked off by an uneven surface or increase of winds with height and the spiral tilts to an upright column. They are called Willy Willys in Australia. 

Sports fields are prone to them, interrupting games as players shield their eyes from the dust and grit. Farmers often spot them in their fields too.