It's suggested that you dry your herb in a dark, dry place. Light degrades THC, especially sunlight. It's not a very stable molecule. CBD (Cannabidiol) break down into THC, and THC breaks down into CBN (Cannabinol). That why you gotta look at the color of the trichs to determine if you have reached the point of diminishing returns (time to harvest). If you left it in the sun too long, you would lose some THC, which would break down into CBN - the part which is believed to be responsible for weeds depressive effect.