Can't answer about the temp/humidity but it looks like you have too much material in some spots, ergo the whiter buildup.
Per VZ, you can wet sand gently till you get it reduced in thickness while being very careful not to start sanding the paint below.
Before you do, make sure you let it cure completely and is hard. You'll know if it's not because it will start galling and balling up on your sand paper.
Wet sanding trick: Keep water moving while you sand. You'll see accurately what the surface looks like, and it will keep your paper from filling up with material prematurely. If I can't use a slow running hose, I use a ZEB spray bottle, medium sprat.
If you're using a rattle can product, It takes some skill to apply correctly.
First, Look for products that have a fan type nozzle, they usually have a flat top that depresses a pin into the valve. The other type is like a source point dispersion, like a loud speaker, more material in the center than the edges. Harder to get coverage.
Practice with some paint on cardboard, maintain the same distance of 8-10" at all times across the surface you are painting.
Deliberately spray beyond the target, as in when you're at the right or left edge
Don't Stop, blow right past the edge then stop. This keep the edge the same as the center.
Lastly, pay attention to lightly overlap each layer, this where practice will help out greatly. Spray one coat of paint, not clear, on a piece of card board 2x2, let it dry then look at your work.
See if you're keeping your distance, and if your overlap is correct. If either isn't, you will see build up, or lack of material.
Repeat on new piece of cardboard. Hope this helps...
