Lets Build a World: Part Eleven: Climate

Last time we worked on starting to map the world, which included working out tectonics. This time we look at the last part of the entire planet build, and that is its climate.

In a typical Earth like world, there are five climate bands; arctic, sub-arctic, temperate, sub-tropical and tropical. That isn’t necessarily the case in all worlds, and each band can have variance based on a number of factors, such as altitude, weather patterns or even more extreme things like the presence of a deity. Adding a second sun could also change things up substantially as well.

Our first step to determine the climate is to work out the mean planetary temperature. Is it similar to Earth, or is it hotter or colder? The hotter it is, the further north people have to live as the equatorial regions become to hot to live in, at least for humans and others like them, whereas the colder it is, the further south people need to live as it may resemble an ice age.

On a 1d100, we roll a 43, which results in a normal temperature, similar to Earth. Not super hot or super cold. Which means we can find people all across the globe.

The next step is seasonal variance. Seasonal variance is produced on Earth by its axial tilt. The more a world tilts, the more extreme seasonal variance is. Of course, axial tilt doesn’t have to apply to fantasy world. There could be other explanation for seasonal variance, ranging from the sun waxing and waning in strength or an eternal war between the gods. A Song of Ice and Fire is an example of a world with extreme seasonal variance.

Rather the roll on the seasonal variation, I instead choose, going with mild. This results in a world with less variation than on Earth, resulting in the arctic circles being pushed back further north, and the ice sheets being smaller. Seasons are present but reduced in strength, with the tropics and sub-tropics seeing no seasonal variation, while temperate and sub-arctic bands have warmer winters and cooler summers.

This could explain why, at least from a scientific view, the world has more oceans. The warmer temperatures in the the artic regions caused the ice sheets to melt and raise the sea levels.

Now we know what the temperatures are like, we have to work out the prevailing winds and ocean currents which drive the weather. For both, north of the equator, they move in a clockwise direction, while south of it they move counter-clockwise.

For currents, take a look at the major bodies of water and draw a circle in the appropriate direction depending on what hemisphere they are in. They will follow along the edges of land masses, which in the case of my map will be the undersea mountains and island chains. In the map below, the currents are marked in blue.

For prevailing winds, they are generated by oceans and large land masses, the latter of which we are lacking. Unlike ocean currents, they aren’t impeded by shorelines, but mountain ranges, especially large ones, will hamper them. For my world, the wind currents are shown in orange.

And that is it for the planetology stage of the world building. Next time we will choose one of the regions on the map and drill down into it, starting the Continents and Geography chapter of the book. And looking at the map, I have a fair idea where I am going to choose.

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