The clouds made a valiant effort, but failed to produce more than just a few sprinkles across western Nevada Tuesday. With that weak impulse moving on to the east, Wednesday’s skies should clear up as we go through the day, and the temperatures will continue to warm up through the rest of the work week. Wednesday’s high in the upper 60s should rise to the upper 70s by Friday, and stay somewhere in the 70s throughout the weekend.

sun diameter

Yesterday, I mentioned there are two reasons why the day is longer than the night on the equinox. First, the sun isn’t a point of light, but rather a disc, and sunrise occurs when the top of the sun appears on a theoretical flat horizon, and sunset is when the other side of the sun disappears. That adds a few minutes.

atmosphere refraction

But there’s another even more important factor. The atmosphere acts as a lens and refracts the sunlight inward, allowing us to see the top of the sun sooner than if we didn’t have an atmosphere. It also lets us see the sun longer after it clears the horizon in the evening. Together they make the day about 20 minutes longer than the night at the equinoxes.

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