Published on [Permalink]

@smokey You mean how quickly night seemed to fall after sunset where I am? I think that’s mostly a local atmospheric thing. Lots of particulates (dust, for example, or haze from humidity, not to mention clouds, of course) can make a dusk linger by scattering more light, but a very clear, clean atmosphere will make the transition from sunset to full night seem quick. (When the sun sets on the moon, it’s like someone flipped a switch. Bright, then dark. No atmosphere to scatter the light.)

Sure, the north–south thing can matter. The further from the equator you are, the winter sun will be slanting through more atmosphere, especially at sunrise & sunset. So winter twilight lasts longer than for those closer to the equator, where the sun is higher overhead for much more of the day, year-round, until it cuts at a steeper angle to the horizon.

But — equinox! — this is one of two times of year when your distance from the poles doesn’t matter: the sun is rising and setting at almost the same time locally everywhere, and therefore cutting through mostly the same volume of atmosphere at dawn and dusk for everyone.

Reply by email