The dew evaporated when the sun rose.

Literal

Dew [topic-は] sun [subject-が] rise-[when-と] evaporated.

露 (つゆ, 'dew'). 蒸発する (じょうはつする, 'to evaporate'). と marks the automatic consequence: sun rises → dew evaporates. Clean cause-and-effect with the natural-consequence conditional.