This is because longer summer days afford the opportunity for more exposure to sun light, and this in turn seems to boost levels of seratonin in the brain's hypothalamus, which regulate the self in relation to the environment. Heat can also affect us, in that it leads to an increase of aggressive behavior. This may correlate to an increase in the summer of testosterone levels, linked to aggression. Negative ions, which have a beneficial effect, are generated by large bodies of water, like the ocean, and water falls. This disorder leads to season-linked depression in many people each year, usually in the winter, because of the lower levels of available light.
Light therapy is the primary, non-drug based treatment for winter depression.
To arrive at the right dose, it's important to experiment with the intensity of the light and the duration of one's exposure to it. Mr. Thurlow says that the New Englander preoccupation with weather may be partly because New England gets a lot of storms, because of its location in relation to east-flowing jet streams. It's also tied to New England's agrarian and maritime past, which made weather wisdom a mainstay of survival. He suggests that frequent forecasting of lots of snow may be linked to the farmer's need for optimism. An early falling snow, and thick winter snow cover, leads to early thaws and the slow release of nitrogen-rich water to feed the soil.