When there is still sunlight at 5pm, and the temperature is just as hot as it is at 1pm, why is the UV index significantly lower in the evening?

Question

When there is still sunlight at 5pm, and the temperature is just as hot as it is at 1pm, why is the UV index significantly lower in the evening?

In: Planetary Science

Answer 1

Temperature is more a quality of the air, not sunlight exposure at that moment. And while there is still sunlight in the late evening the angle at which the light arrives means it travels through more atmosphere to reach the ground. It is still plenty bright to see by but the UV light has more opportunity to be absorbed and so your exposure is much reduced.