What type of clouds make the Sun UV rays that much stronger to strongest? Why?

Question

Are the Sun rays less strong when its just "sunny" as apposed to a "cloudy" day? I've heard "The Suns rays are double because they bounce off the clouds." What about when it's thick clouds and it seems to be darker than an "average" day?

What season is the Suns rays strongest and weakest. Winter, Spring, Fall, and Summer.

What hours of the day are the Suns rays strongest?

Does black absorb light rays more than white?

Do UV rays bounce off white surfaces more than black?

Thank you.

Answer 1

Ultraviolet light has greater penetration than visible light, which is why it still present even when it is cloudy. There is less visible light reaching the surface, but ultraviolet light stays about the same.

It depends upon location on Earth. People at the equator have it the worst all year round. If you are in the U.S., then summer is when ultraviolet rays are most intense.

Ultraviolet rays are most intense between 10:00 A.M. and 4:00 P.M.

Yes. That is why it appears darker. There is less reflected radiation for your eyes to detect.

Yes they do. Both UV and visible light do that.

Answer 2

I don't know if I can completely answer all of your questions, but I'll start with the easy ones, and go from there.

Yes, black things absorb more light than white things.  That's what makes them black, but that only applies to visible light.  UV is not visible, so looking at the color won't necessarily tell you if UV bounces or is absorbed.  Here's an example with a kind of light on the other end of the visible spectrum.  Infrared light is not visible, but some black-and-white cameras use it to see.  I had a black and white webcam that saw IR light, and it was weird to see my roommate wearing his black hat on camera because his hat looked white in the picture.  Everything else looked normal, but his hat was white.  So even though his hat absorbed most visible light, it reflected IR light.  The same can be true of UV.

The sun's rays are about the same regardless of the season.  However, the tilt of the earth means that the sun's rays hit the earth more directly in areas that are in Summer, and at an angle where it's Winter.    You can use the same idea to determine what time of day has the most intense sunlight.  The higher the sun is in the sky, the more intense the light that reaches you.

Overcast days definitely do not have more intense IV than sunny days.  People may think that because the sun doesn't feel warm, so they don't think they're getting burned.  So they'll stay out longer, and they won't wear sunscreen.  When they get a sunburn, they may think that the UV must be higher because they didn't get a sunburn on a sunny day, but the real difference was how much much exposure they got.

I hope this helps.