One of the easiest ways of locating soaring monarch butterflies is to rely on the presence of soaring birds, such as gulls, hawks, vultures, swallows, or swifts, to mark a thermal and examine the air in their immediate vicinity. If the season, wind, and temperature conditions are favorable and the butterflies are reasonably abundant, they apparently exploit most thermals, including those with birds. Locate the birds, and you locate the butterflies. A wind that changes direction and velocity frequently indicates that thermals are drifting through and past your site. Dust devils are organized cores of plume thermals.
Clouds associated with thermals include low to mid level cumulus clouds, and cumulonimbus clouds.
Thunderstorms, tornadoes and hurricanes are also associated with strong lift but are best studied from a great distance. Structure of Thermals Thermals are convection systems that range in diameter from a meter or less near the ground to a thousand meters or more at several thousand meters above the ground. Thunderstorms are giant thermal systems and often have more than one convection cell. The first diagram on the right illustrates a vortex ring thermal, the diagram on the left shows a plume thermal. In each case, straight black arrows indicate wind direction, curved black arrows shows the circulation of air, and red arrows indicate the flight path of a butterfly.