SF writers having fun with seasons

As a writer, you can do all sorts of fun worldbuilding stuff with seasons. The English-language concept of Spring-Summer-Autumn-Winter is based on the European seasons. Even on Earth, it doesn’t hold everywhere.

In northern tropical Australia, where I used to live, you have two seasons:
A dry season, when–surprise, surprise–it doesn’t rain, and a wet season, when it’s supposed to rain but often doesn’t, and if it does, it does so in quantities no drainage system could possibly be built to cope with, and in between these bouts of liquid air, it’s just horrible and humid.

Even in Sydney, we have only three seasons. Autumn very slowly morphs into spring, as the European benchmarks for winter–long nights, bare trees, and snow–just don’t hold. Many trees never lose their leaves at all, and some only do so well into spring, and even some of the European trees appear mightily confused.

On your imaginary world, you may choose to adhere to the basic four-season model, but if your setting has a dry or tropical climate, the seasons will be different.

But why not do something more challenging. Let’s go back to what causes seasons. Two things:
1. the inclination of the planet’s axis of rotation compared to the plane of rotation.
2. physical distance of a planet to the star.

Factor 1 is by far the most important on Earth. It is why we have summer while the northern hemiphere has winter. Factor 2 requires an elliptical orbit. No planet has an orbit that’s 100% circular. Earth’s orbit is pretty darn circular, but still, Earth is closest to the Sun in January and furthest from it in July. Therefore, the summers in the southern hemisphere are slightly warmer than summers at similar latitude in the northern hemisphere, and the winters slightly colder. Still, when you consider other factors of topography, this effect is so small as to be meaningless.

Supposing you were on Mars, the facts would look very different. Mars has both an inclination and an elliptical orbit. Therfore, the winters on the southern hemiphere of Mars are noticeably colder (and longer, since a planet moves faster the closer it is to the sun) than those on the northern hemispere and the summers noticeably warmer. However, the inclination of Mars is still similar to Earth’s.

Now imagine if you were on a planet rotating perpendicular to the plane of orbit. We have such a planet in the solar system: Neptune. If you stood on the north pole of Neptune in the northern summer, you’d have the sun not only permanently above the horizon, but straight overhead, as in the tropics on Earth. In winter, the sun would disappear for months. The sun would only rise and set every day on the equator. How would plants and animals survive on a world like this?

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2 comments on “SF writers having fun with seasons

  1. In the book West of January by Dave Duncan each day takes decades. Civilisation uses giant turtles as vehicles to move along in a permanent dusk, avoiding the freezing of night and the boiling of day.

    It’s a good read, like all of Duncan’s books.

    • I’ve read stories set in worlds like that. Like Venus, or worse. Excellent opportunities for worldbuilding that’s really different.

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