Well, for your situation, I can give some reasons. First, it can be the light problem. As we know that the light is so strong that when we go out and open our eyes to see it, it will just make the eyes be hurt. And also our eyes are so very sensitive that they will react to the stimulation from sun light. When the sunlight gets into our eyes, it will make our eyes to adjust to it. And at this time, it will water. So it is very normal. Second, it can be because of the dirty objects in the air outside, so when you go out, your eyes are easy to be infected by them. In this situation, we can say that, it can be possible that you are getting the dry eyes, for dye eyes are caused by the irritants. So just be careful about it. For your situation, maybe you should go and see a doctor so that you can talk about your problems, then can have the eye exam. Also, before you have an eye exam, you are not supposed to have your eyes exposed under the sunlight for a long time, also should be careful about the dirty things outside. Anyway, just be careful about it.