While world building, I came up with a planet that had the combined traits of very rough and rugged terrain and small seas.

The planets surface is covered with mountains and hills are common place, along with ravines, valleys and plateaus; my inspiration came from looking at tree bark.

The planet only has one real ocean. I'm not sure exactly where I wish to place it, probably around the middle, dividing the sphere. With the exception of lakes that erupted from subterranean sources, all the water on the planet is a tributary of the great sea, multitudes of rivers, lakes and small seas.

My question is, what sort of climate would arise from my premise.


3 Answers 3


Water has the highest specific heat of all substances. Large oceans collect huge ammounts of heat slowly during the day and release such heat slowly during the night. When the sun is shining above a portion of the planet, the seas absorb a lot of heat decreasing the overall temperature when compared to a planet with a bare rocky surface. During the night, when the sun is not shining, that sea releases such heat to the atmosphere, creating wind. Effectively, seas damp temperature differences. But, for large seas on earth, this effect is limited to the mass of land immediately close to the seas. This is called continentality.Land far away from the sea registers bigger temperature differences between day and night, winter and summer etc, we say that lands away from the sea have a greater continentality, so they are subject to greater temperature gradients etc.

If you spread the water as various smalls bodies of water, you effectively decrease all of the planet surface's continentality, all land will be close to water, so the water will effect the temperature of the entire landmass of the planet. No land will be too far away from water to have a large temperature swing. But, as a side effect, the smaller masses of water will have a smaller capacity to store heat, so the effect of the oceans on the temperature - the capacity of the oceans to damp temperature changes - will be smaller.

Regarding the rugged terrain, montains have the effect of forcing winds to climb. If such wind spend time over a mass of water, it will be carrying water vapour, its humidity will be bigger than normal wind. So, if this wind is forced to climb the mountain range, you will have an area with almost constant heavy rains. Hot and humidy wind that is forced to climb loses temperature, and consequently capacity to carry water. The water falls as rain and the air loses humidity. Upon crossing a mountain range the wind becomes cold and dry. Valleys between the sea and the mountain ranges will be very humid, with lavish vegetation and ecosystem. Valleys after the mountain ranges will be cold deserts, unless they are big enough - and positioned near the equator, to re-heat the wind, a situation where they will become hot deserts due to lack of water.

The planet will not be very windy, because wind is the result of air masses being heated by surfaces that are exposed to sun, the larger those surfaces, the more mass of air is moved as the air heats and expands. If the valleys are completely blocked by mountain ranges, wind has nowhere to go execpt upwards. This will create thermals. If the valley has access to water (its not a dry valley), water vapour will climb with such thermals and create cumulus-nimbus clouds. This kind of clouds are able to generate thunderstorms, heavy rain, blizzards etc. As your sea is small, there will be low capacity to form thyphoons and cyclones. Metereologic patterns will be small, divided in sectors by the huge mountains. Expect a lot of deserts everywhere the land is blocked access to water masses due to mountains.

There will be a lot of mountains with cold tops, forming a lot of ice. If the planet experiences big temperature swings, the ice will tend to melt and form rivers. Rivers will have a big difference between their summer time flow and their winter time flow. Valleys will tend to suffer floods. Rivers will have furious streams. Erosion will be quick due to rivers. Expect to have big canyons over several million years. This can create seasonal rivers. Deserts are more prone to this.

The source of water for the planet will have an effect on water distribution. A bit of water comes from vulcanism. Water trapped inside the planet exits the crust via vulcanism, so if you have distributed mountain ranges, you have distributed water. But, usually, the major source of water for a planet are the comets and asteroids that are rich in water and hit the planet. Planets in young solar systems suffer bombardments of asteroids. This - if we dont consider other variables - allows a random distribution of water over surfaces. This means that the mountain ranges will divide portions of water across the globe. Each valley will have its share of water, effectively creating microclimates. If a valley was unlucky on its share of asteroid/meteors carrying water, and the mountain ranges are trully tall enough to block water/wind passage, such valley will become sterile. On the other hand, valleys with a lot of water will become quite humid, as oasis.

Well, its hard to say, climate is very complex, but those are good rules of thumb to allow you to create a fictional climate for your world setting.


Expect heavy rains in the mountain ranges facing bodies of water and arid climates in valleys blocked from the sea.

  • $\begingroup$ This map upload.wikimedia.org/wikipedia/commons/e/e6/… of a terraformed mars was a major aid in visualizing the planet. This world probably has a lesser percentage of it's surface covered by water than earth. What water that is there is broken up by terrian,with the exception of the equatorial ocean. $\endgroup$ Mar 9, 2015 at 9:15
  • $\begingroup$ This is way more water than i was expecting... $\endgroup$
    – Jorge Aldo
    Mar 9, 2015 at 12:38
  • $\begingroup$ Can you make a map showing the mountain ranges ? $\endgroup$
    – Jorge Aldo
    Mar 9, 2015 at 13:03
  • $\begingroup$ Unfortunately No. I've never experimented whit map making, wouldn't even know what software or service to use. Mars as Mundus Magicus, has elements of how this world is supposed to look; the land masses divide in half by a single ocean. Though it's nowhere near as arid my world would be. A rugged land scape checkerboarded by deep rivers and lakes is what i see. $\endgroup$ Mar 9, 2015 at 17:14
  • $\begingroup$ With this map, the climate would be very different from what i described. For example, at the south pole, covering a large swath of land you will have a cold desert. In the area named elysium you will have equatorial forests and a huge volume of rain. Tempe terra will have huge rains and forests too. Because water cant circulate up and down the equator, heat will be traped there and only athmosphere will be able to spread heat. Air has much less specific heat than water. But, without the moutains we cant predict much. $\endgroup$
    – Jorge Aldo
    Mar 9, 2015 at 17:53

I found that interesting that you have only one ocean. It would be located on the equator if I understood correctly? One characteristic of this configuration is the impact it will have on the global temperatures. Like user3453518 mentioned, ocean are great to distribute the heat on the planet. On Earth, it's done by having the cold waters mixed with the hot waters. But here, you have no north-to-south ocean to do that. Most of the water stays near the equator, meaning the water will be hotter. The whole equator will be hotter.

On the opposite, latitudes closes to the poles will be colder because they lack this source of heat.

The impact could be significant. If you want an idea, you can look at the difference in temperature between Europe and the American North East at same latitude. Europe is affected by a hot (not so hot) water current and North America is affected by water form the Arctic. I should also mention that the climate is considered oceanic in Paris but continental humid in Quebec, although Quebec receive more precipitations.

The difference in temperature during the coldest month between Paris and Quebec city is a whooping 17,8°C. But only 1,3°C in summer.

  • $\begingroup$ I should have included the effects of ocean currents in my answer... Wind currents are less important than ocean currents when predicting the metereology of a large landmass connected to a body of water like a ocean. $\endgroup$
    – Jorge Aldo
    Mar 8, 2015 at 22:02
  • $\begingroup$ astrobio.net/topic/exploration/moon-to-mars/if-we-had-no-moon Where it not for the moon much of earths surface water would be around the poles. that fact was floating around in my mind when i positioned the ocean. $\endgroup$ Mar 9, 2015 at 9:07

As the others have said, Oceans do a lot to regulate the temperature of the Earth. Having the ocean around the equator would likely keep the equatorial region similar to ours, warm and humid year around. The deserts would likely be north or south of the this where there are large mountain ranges between it and the ocean.

Here on Earth, the ocean currents mix the waters north and south, warm water is always moving north by Europe, and south by NE US. It is also warm down south america toward Antarctica and cold up the western coast of Africa.

So it is constantly evening out the temperatures across the globe. This is both on a daily (day/night) cycle and seasonal cycle (winter/summer) etc. It help push moisture into the air everywhere which will later fall on land.

So there will likely be many more micro-weather niches. a sea stuck in a mountain range will affect the local weather. The great lakes affect a lot of the weather around them, Michigan get 'lake effect' snow storms all the time.

However, without large north south oceans, it is likely that the farther you get away from the equator, the more extreme the winter and summer seasons will be from each other. Larger bodies of water will have localizing affects and even it out a little but it would be more local weather patterns. Kind of like Duluth/Superior weather vs. Winnipeg.


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