Wind and rain make sure that all kinds of dirt are blown and washed away. A nice sunny day without any wind doesn't wash this dirt away, therefore smog can form.
Slide 7 - Tekstslide
Slide 8 - Video
Slide 9 - Tekstslide
Exercises
Continue with the exercises of paragraph 2.7. Homework: exercises 2 to 6 of paragraph 2.7
Done? Continue with exercises 1 to 3 of paragraph 2.8