It can if you wet it and apply neat fresh lemon juice, then sit in the sun for about one hour. You will need to wash and apply a good conditioner afterwards as it will dry your hair out a bit.
only if you have light coloured hair already. this might sound wierd but try squeezing a little bit of lemon juice on your hair, apparently enhances the sun's bleaching effect.
Yes, sun exposure can cause your hair to lighten...you can do things to encourage that (such as add lemon juice to your hair) if you want it to occur...
If you want to protect your hair from the sun, wear a hat or scarf over it if you are going to be out for extended periods...a few minutes here and there aren't likely to make any difference..
It sure does! The degree of the suns effect depends on how long you are in the sun and how dark your hair is. My hair is golden blonde and turns white during the summer. My boys have light brown hair and in the summer they are pretty much golden blond - but they spend a lot of time in the sun.
Yes, Not dramatically, -Say from brown to blonde for instance, But, There is a product called "Sun In" That you can spray in your hair before going out into the sun which maked the effects more dramatic.