There is no doubt that when it's a clear sunny day, especially after a few days of cloudy skies, the mood seems to lift with a sense of lightness and joy.  This is a natural response to sunshine!

Aside from brightening up the mood, sunshine has an even greater positive effect on the physical health.  
Let's break down some of the benefits:

Vitamin D

Have you heard of Rickets, also known as Osteomalacia?  This is the softening or weakening of bones due to a deficiency of vitamin D, which is essential for the body to properly absorb and utilize calcium for strong bones.  Unfortunately with the grown of technology, most humans spend more of their time indoors.  Since our body actually has the ability to make its own vitamin D from direct sunlight exposure, this kind of indoor lifestyle inherently depletes the body of vitamin D.  There's no doubt that less sunlight exposure has a negative effect on our health, probably much  more than scientists have discovered.  So make it a habit to get outside and expose your skin without sunscreen, making sure not to allow yourself to burn.  It also doesn't hurt to supplement with a good WHOLE FOOD vitamin D.  I want to say that with caution, because I'm not a fan of most vitamin D supplements.  Be sure to investigate my take on supplements in the Nutrition section.

Metabolic Health

According to studies, sunlight can penetrate so well through your skin, you could even read a book form inside your own skull.  That's pretty amazing!  This comes in pretty handy when going out into direct sunlight after eating a nice green salad.  According to this article "Sunlight is the most abundant energy source" and what was discovered is not only chlorophyll containing plants can convert sunlight into biological energy in the form of ATP.  Just to summarize, all mammalian mitochondria (energy producing part of our cells) can produce ATP (energy) when chlorophyll is present in the blood stream with the presence of sunlight exposure.  That is incredible!  We are truly fearfully and wonderfully made!!