is this what an evap looks like?

i took this yesterday, and this morning I saw this. yes I know its over the time frame, but ive never had an evap on one of these tests. ive been conducting some expirements(I know I'm weird lol). and even after leaving them out in the sun, ive never had one. I guess its the weirdo in me, but I wanted to know how long and under what conditions. do they appear(as so many people ive seen question this too) but I need your guys help, if you can be so kind.