We found that individuals awaken in a good mood that deteriorates as the day progresses — which is consistent with the effects of sleep and circadian rhythm — and that seasonal change in baseline positive affect varies with change in daylength. (science.sciencemag.org)
potential production estimated production of a crop under conditions when nutrients and water are available at optimum levels for plant growth and development; other conditions such as daylength, temperature, soil characteristics, etc., determined by site characteristics (ipcc.ch)