A clock outside the Senate chambers. Nearly everyone in the United States will turn their clocks ahead one hour at 2 a.m. Sunday. (Oliver Contreras for The Washington Post)

Would you trade a one-time hour of sleep loss for an entire season of later sunsets? You won’t have much choice in the matter Saturday night. After four months, we’re set to return to daylight saving time.

We’ll turn our clocks ahead one hour at 2 a.m. Sunday, effectively making it 3 a.m. (So don’t schedule any important meetings at 2:30 a.m., because that time won’t exist Sunday. It’s also not a great time for a meeting, anyway.)

We lose an hour of sleep but only for one night. It’s just to shift us toward later sunsets until November.

Of course, this will come with later sunrises, but most of us would prefer that sunlight at the end of the day, after work, when we can enjoy it. Waking up in the dark seems like a fair trade.

In Washington, the sun will set at 6:08 p.m. Saturday and 7:09 p.m. Sunday. Sunrise times will “spring forward,” too, with Saturday’s 6:29 a.m. wake-up pushed back to 7:27 a.m. on Sunday.

The sun sets in Boston at 5:43 p.m. Saturday and 6:44 p.m. Sunday. Bostonians enjoy their first 7 p.m. sunset on March 24 — lagging two weeks behind the D.C. area and four days after the start of astronomical spring.

And in Philly, Sunday morning’s leap takes sunset from 6 p.m. to 7:02 p.m. Sunrise will be bumped up from 6:22 a.m. to 7:20 a.m.

The exception will be Arizona, which, save for the Navajo Reservation, remains on daylight standard time all year long. That means they’ll keep the earlier sunsets. Their logic was that the characteristically hot climate meant cooler, darker evenings would be a welcome respite from the heat.

After a winter of short days and cruel sunsets sometimes falling before 5 p.m., many in the Northeast and Mid-Atlantic yearn for the commencement of daylight saving time. It heralds the first noticeable step to springtime, with the weather eventually following suit and the days becoming longer. In fact, the days grow longer by a greater margin during the next two weeks than at any point all year. Daylight is increasing by roughly 2½ minutes each day.

The annual shortening of the days in the months leading up to winter — and gradual regaining of sunlight in the spring — comes thanks to Earth’s 23.5-degree tilt on its axis.

Regions near the equator experience the most direct sunlight averaged over the year, which is why the tropics are the warmest. On the equator itself, every 24-hour period is divided into equal parts day and night. That’s why every day is exactly 12 hours long. The same is true about night. Sunrise and sunset times might wobble a few minutes up or down over the course of the year, but the length of daylight will never change.

Near the poles, it’s a different story. Earth’s tilt means that regions in the Arctic or Antarctic can be facing away from the sun in the shadow of other parts of the globe for weeks or even months at a time. That’s the premise behind “polar night,” during which the sun plunges below the horizon around the start of winter and doesn’t emerge until spring approaches. Utqiagvik, Alaska — the northernmost town in the United States — is shrouded in inescapable darkness from Nov. 19 to Jan. 22 each year.

In the summertime, that effect is reversed. The sun doesn’t set in Utqiagvik between May 11 and Aug. 1. Talk about a long day.

Day length varies the most at the poles and least at the equator. In between, the annual variability is a bit more moderate. In Chicago, the difference between the shortest and longest day of the year is 6 hours, 6 minutes. Closer to the equator in Miami, that difference is 3 hours, 14 minutes. And during the summer, days are longer in Chicago than in Miami.

How can that be? After all, Miami’s average annual temperature is 27 degrees higher than Chicago’s. It has to do with sun angle. Every place on Earth gets the same number of hours of daylight if you added them up over a year. But not all sunlight is equal. Closer to the equator, it’s more direct. Near the poles, it comes in at a sharper angle, meaning the same beam of light has to warm a greater stretch of land — and the effective warming is less.

Sun angle is also also why we have seasons, the angle of the sun above a given location varying over the course of a year during the earth’s orbit about the sun. It’s earth’s 23.5-degree tilt on the axis that causes the sun to appear higher or lower during certain parts of the year.

Standard time – by which we abide in the winter – is what we would ordinary have year-round. Daylight saving time sprung about to better serve an agricultural and industrial populous during the traditionally warmer summer months.

It was believed that the daylight would be more useful in the evening than the morning, so the summertime clocks were shifted ahead in an attempt to move peoples’ schedules up. If it wasn’t for the advent of saving time these 8 months of the year, we’d be stuck on standard time year-round. Many have proposed abolishing standard time, keeping daylight saving time the norm all year long.

Most 21st-century Americans dislike the current system of switching clocks, preferring instead the idea of making summertime saving time the norm year-round. It’s gaining traction in governments.

A new bill introduced in California would do just that and has been met with overwhelming support. If passed, the Golden State could lead the nation’s fight to abolish winter’s standard time. The San Francisco Chronicle reports that at least 28 other states have some form of legislation seeking to do the same.

Correction: The original version of this article had an inaccurate description of standard time. It has been updated.