World Map - How can I tell if the Ecosystems are realistic?

I'm trying to create a world map for my fantasy novel. My problem is that I love designing things, and I'm finding myself bogged down with figuring out how desert A got where it is, and how plain B's temperature is different than plain C, and so on. I've never studied that type of thing in any great detail, so my knowledge of how the different ecosystems form is limited.

This has led me to ask the following question: how can I know if a map is realistic?

For the majority of readers, knowing that plain G would be cool instead of hot, or that a forest would require more rainfall than is mentioned, is not going to be a problem. However, there will invariably be the one person who knows how all those things work, and if the impossibility of the map really gets to him, it could sour his reading experience. That's not something I want.

So how do I know if a world map is realistic, short of knowing how every ecosystem on earth forms? Is there a cheat sheet?

Post-Answer Note: While I've marked the answer by John, it's not the one that helped me. It does answer the question, but what I ended up using was the resource linked by Monica in the comment below. It was detailed but still simple enough to provide exactly what I needed. I was able to create a realistic world in a matter of hours, and have zero doubts about whether or not it is realistic.

First it is always possible to educate yourself, you can find secondhand or old edition textbooks fairly cheap just find a beginners Climatology, landform geology, and Meteorology book. learning the basics in not that hard.Continuing education classes and even Khan academy videos are also options.

Second, here is some bare bones basics just to get you started. I am sure other will have many things to add to the list. I have bolded the important take aways. There are a few basics worth considering, and that make bad maps easy to spot.

1. Landform, nothing gives away a bad map faster than landform. Continental rock mass tends to break at a 120 (or 240) degree angle and the majority of the earth's coastline is made by connecting these angles. big sweeping smooth curves or long straight lines are just unnatural in a coastline and tend to stick out. Mountains are rarely isolated and tend to run in ranges. Also mountains come in many shapes not just curved pointy cones. Incidentally if you have your mountains and coast laid out most of the map will make itself if you have the basic knowledge.

2. Rivers. I don't know how many maps I have seen with rivers that start in the middle of nowhere. Rivers start small and numerous in the mountains and run down hill, getting fewer and larger as they go and connect, most eventually reach the ocean. The closer the mountains are to the coast the more unconnected rivers you will get. Here is a map of the river systems in the US to give you an idea.

3. Rain, wind tend to come from one prevailing direction in a region and mountains cause moist air to drop its water as it rises, this creates a rain shadow effect. One side of a mountain range is always drier, which side is determined by the major winds. If you have jungle on one side of a large mountain range the other side will tend to be much drier. If you want a drastic changes in rainfall over a short distance you need a reason, mountains in between are usually it otherwise changes should be more gradual, deserts don't suddenly change into rainforest. Change tends to be gradual

4. Climate belts AKA climate zones. the planets spin combined with drag in air movement creates zones of different climates on earth. the same zones with hot jungles also have hot deserts. The other facet of this is major air cells these zones are also created by large moving air cells, All you really need to know is rising air drops rain while falling air from these cells creates deserts.this means rainfall patterns also tend to run in belts across the planet. It is basically impossible to get a jungle or desert or any ecosystem that stretches too far north and south. 5

Lastly Sometimes less is more, smaller local maps are easier to do than large global ones, by removing many variables like jetstreams and ocean currents you can skip a lot of those problems.

• I would just add that rivers may "start" from headwater marshes, not just from mountains (not sure if that counts as "in the middle of nowhere"). While mountains can collect rain water from the rain shadow effect you mentioned and thus might frequently form headwaters at their bases, North America's largest river notably does not originate from mountain tributaries. Jun 8, 2017 at 19:46
• Its mostly semantics about what counts is "in the mountains". What river are you talking about because the mississippi is fed by many many mountain tributaries.
– John
Jun 8, 2017 at 20:22
• The headwaters of the Mississippi are in the mountain-less Midwest, so a macro-scale map would show it starting in those marshes "in the middle of nowhere"; but you're right that it is joined by the Missouri, Ohio, and Tennessee rivers which do originate in mountainous regions. Jun 8, 2017 at 20:37

Earth, your cheat sheet is earth. You are not an expert and you don't need to be. Chose an ecosystem for your starting location, then decide where the action goes in relation to that place. Where is the planet getting the most prolonged contact with its star? It will be warmest there. Proximity to an ocean or large body of water makes it more humid but also more temperate:

Large bodies of water such as oceans, seas, and large lakes affect the climate of an area. Water heats and cools more slowly than land. Therefore, in the summer, the coastal regions will stay cooler and in winter warmer.

Altitude also affects your climate. The higher up you go, the lower the temperature:

For each 1,000 foot rise in altitude there is a 4°F drop in temperature. For example, if at sea level the average temperature is 75°F, at 10,000 feet the average temperature would be only 35°F.

Deserts form due to many factors but have extreme temperature shifts because sand reflects sunlight but does not store it long, leading to hot days and freezing nights. Between extreme ecosystems, there must be a substantial transitory territory (except in the case of altitude, where the transition is shorter and more vertically inclined.)

Finally, when in doubt, check if analogues to your fiction exists in some way in reality. This isn't "cheating", it's a way to ground your player and helps him suspend his disbelief.

• You can write links in markdown like this: [This is the text shown in blue.](this/is/the/link) Jun 6, 2017 at 6:44

Put your story in a real place on Earth, then change the names. Robert Howard did a great job of this with his Hyborian Age. If you spread out his world and drop the Mediterranean in it is Europe, Africa, the Middle East etc. Of course the premise was that the Hyborian age was actually the remote past of the real world so it should be similar. I have read that Sword of Shannara did something similar: the world is basically North America.

This maneuver makes weather and geography easy, because the author can just pull the details in from the real world. Just look it up.

If you are wondering where to place mountains and valleys, remember that mountains exist for a reason. Most mountains are created when two plates of crust push against each other. So, they tend to be in rows.

Also, mountains are sharper when they are new due to the effects of erosion. Using the US as an example, we have two major mountain ranges: in the West and in the East. The western mountains are newer so they are taller and sharper. The eastern mountains are shorter and rounder because they have been worn down over time.

Mountains can also be created by volcanic action. They often exist in newer mountain ranges as the cracking of the crust allows magma to find it's way up. However, they can occur other places as well due to a hot spot under the crust. Since the crust moves, there will be a string of this kind of volcano. The Hawaiian Islands are an example of this kind of volcano. You can also get volcanoes where the crust is being pulled apart. Most of that occurs in the oceans but it can happen on land (as is currently happening in Africa). That area will become a new sea but that won't happen for a very long time.

Once you have the shapes of the land and seas from deciding what is moving where, figure out prevailing winds. You can use the Earth for a model of that.

You can also figure out ocean currents. A very simplified version of ocean currents is to draw clockwise circles (counter clockwise in the southern hemisphere) in every big body of water and then draw smaller circles near land masses where there are hallows in the coast. Things are actually more complicated than that but this will rough it out. Where the current travels from the pole toward the equator, it will pull colder water and the air that passes over it will be drier. Where the current rises from the equator to the pole, the water will be warmer and the air passing over it will pick up more moisture from evaporation.

The windward side of mountains will always have more moisture than the leeward side. Swamps happen in flat spots where water drains slowly. This usually happens in slow areas but could happen at elevations that have poor drainage.

This will allow you to rough out your terrain and climate but there can always be local oddities. The Earth has plenty (Grand Canyon, salt flats, Yellowstone geysers, Butte Montana, etc.).

Knowing how every ecosystem on earth forms actually isn't that complicated. You really only need to know two things: how hot or cold it gets in an area, and how much water it gets and when. Places near oceans are usually wetter than places that are inland and/or blocked off by tall mountains; cool wet places will experience snow in the winter, while places that are rainy and warm all year round become rainforests. Depending on the size of the continents in your world they might experience on earth as well.

After that it's just a question of knowing what types of plants and animals are likely to be found in what climate, for which earth can be a pretty good cheat sheet. I've also found Geoff's Climate Cookbook to be a useful resource in this area.

• To summarize your answer, the science behind climate and landforms is not very complicated. You say this with no references whatsoever. Jun 6, 2017 at 3:04
• To provide an example of how complicated climatology actually is: Brazil and Kenya are both coastal countries on the Equator, but have vastly different climates. Jun 6, 2017 at 12:25
• Not that complicated? It's most certainly complicated; I've tried to work out climates on a fictional map before, and doing it accurately has a lot of steps to it even after creating a detailed altitude map of your world and deciding on stellar/orbital characteristics. Inferring ocean currents, then wind patterns and high/low pressure zones, then rainfall from those, on to temperature, and finally a proper climate map. It takes more than one draft, without a doubt. And even then, you only have your climates; that gives you a good indicator of ecosystems, but not an ironclad description. Jun 6, 2017 at 14:52