From what I understand thermals are warm ground air that rises as the area heats/warms up in the morning and fall in the evening. You need to get an aerial photo and a topo map with elevation numbers on it to understand how and when they rise. In my opinion you might want to stay up on a ridge in the morning rather than being down low. If you are down low and the thermal rises it leaves you scent on whatever on the way up. Where as if you are on top of the ridge your scent rises into the atmosphere leaving less scent behind. One other aspect that should be relized is that a deer using thermals to scent check for other deer in the area. If you look at your topo map and figure out how thermals work and how they will work in stages according to the elevation. A deer will use these thermals while cruising in the morning and the evening. Feel free to correct me if I am wrong.