Sun: When its closest and when its farther away? If the sun is closest to the North American Hemisphere in the winter than it is in the summer, why doesn't our faces and hands tan and/or blister quicker? Please provide two hyperlink sources with your answer.  Thank you.
 A: Earth is only about 3% closer to the Sun during the northern-hemisphere winter, which means its intensity would only increase by a maximum of about 6%. There is more atmosphere to block out the UV rays that cause tanning and burns due to the shallower angle of incidence. You tend to wear more clothing (gloves, scarf, etc) that blocks the rays. It's cold, so I doubt a lot of people spend a lot of time outside just sitting around with their faces and hands towards the Sun and it would still take some time to get a noticeable tan with only a 6% increase in intensity and a decrease in the UV band from the longer path through the atmosphere.
TLDR: Many possible reasons contribute.
A: That's because the sun is shooting the light at such a small angle that the light have to travel trough the atmosphere for a longer distance. And the atmosphere will decrease the luminosity of the sun. If we could move with the earth in the outer space without rotation, then we would find that the sun is flying upward and downward, drawing a sine wave in the sky. And in winter, the sun will shoot the surface of the earth at a small angel.
