There was a time in Earth's history when a rough analogy to your world existed. North America and South America had just broken away from Europe and Africa. India was out in the ocean. Antarctica and Australia were breaking apart from each other and from Asia.
It was a wet, warm world, because both poles were:
1. Free of land masses at and within 10 degrees of the pole:
2. Warm ocean currents had free access to both poles, coming from a single, vast ocean (the now greatly shrunken Pacific.)
The Earth differed from today in some remarkable ways:
1. At high latitudes, such as Siberia, winter nighttime temperatures remained fairly warm, despite the immensely long nights. I'm guessing that, the effect seen in Europe today in the winter (that continent is warmed by a constant moist flow off of the Atlantic) was prevailant in Siberia, Northern Canada, and Alaska.
2. Shallow inland seas covered much of the continents, because the ocean levels were hundreds of feet higher than today (for example, if you raised sea level 200 feet today, you'd convert the Amazon Basin into a shallow inland sea.) These seas produced much of today's sedimentary rock; at that time, very very extensive swampland existed.
3. The oceans were, as mentioned, warm. The temperature at the bottom of the oceans was between 60 and 70 degrees Fahrenheit.
Your world might be like this.
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Do you wish a colder world? It is easy enough to make one: you simply declare it's colder.
There IS a historical case of the Earth freezing over despite both poles being ice free. It occurred 700 million years ago, and they call it Snowball Earth.
At that time, plant life under the waves in the ocean and natural processes removed most of the carbon dioxide in the planet's atmosphere, and this should have caused a cooling effect. However, the fact that both poles were ice-free caused a warming feedback to occur that prevented cooling until nearly all of the atmospheric carbon dioxide disappeared, and overcame the warming feedback.
Then, overwhelming cooling began, and when it was done, the entire planet had frozen over. At the equator, temperatures were slightly cooler than in interior Antarctica today.
Note that the sun was less luminescent back then, and this obviously made a big difference.
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Perhaps your world has a large difference between day and nighttime temperatures, like Darkover? It heads up to 75 degrees during the day, but falls to 15 degrees at night? The air is not good at holding in heat.
Thus, in the summer, it rockets to 100 during the day, but falls to freezing at night? During the winter, it goes up to 40 during the day, but - 40 below at night?
Tibet has a climate somewhat like this, since it is at high attitude (but not so extreme.) Darkover (by Marion Bradley) seemed to have a climate like this, except colder.
Perhaps your world has little difference in day and nighttime temperatures? It goes to 55 during the day, then falls to 50 at night?
In the summer, it heads to 70 during the day, then 60 at night. In the winter, it goes to 55 during the day, and 45 at night?
London, England, has temperatures like these. Maritime climates tends to have little climatic variation between day and night, regardless of relative warmth.
In our real world, the temperature drops 3.3 degrees Fahrenheit per 1,000 feet that you rise in altitude. The drop is 5 degrees per 1,000 feet if the air is dry. On hot summer days, the decline can be steep in the first few thousand feet of the atmosphere. Our freezing line rarely gets about 16,000 feet in the temperate latitudes.
Yet on chilly Darkover, it rose above freezing at 17,000 feet in the summer during the day, regularly. Darkover had a much slower drop in temperature as you rose in altitude. The atmosphere was denser at high altitudes as well, which might or might not explain that.
Perhaps there are sources of magical cold and warmth on your world, that affect large areas?
Consider the consequences if there are (in the Forgotten Realms, Anauroch is an area of magical heat, and the Great Glacier is an area of magical cold, to give examples. The entire southern two-thirds of the Flanaess (Greyhawk) are magically warm ... and the climate abruptly goes from warm temperate (or even subtropical) to subarctic in the northern third of that area.)
If a big hot area exists, perhaps the prevailing westerlies go up and over this area to the north? This brings abnormal rain and storms to areas that should be dry. It brings abnormal heat on the western side, where the westerlies head north, but abnormal cooling on the east side, where the westerlies head south.
If a big cold area exists, perhaps the prevailing westerlies head south and around this area? If so, they bring unnatural cold on the western side and unnatural heat on the eastern side, as they dip south and then head north.
Or perhaps the westerlies do as they please, and run right into these magical areas?
If the area is magically hot, then hurricanes, constant cloudiness, torrential rain, and humidity are the result. Perhaps truly violent storms occur inland as cold air tries to enter the region, and meets with superheated air from the magic.
If the area is magically cold, then perhaps blizzards are common, and glaciers run out of the area into adjacent areas. In the summer, cold rains are common. High winds occur due to unnatural temperature differentials.
Just some food for thought. What is the atmosphere of your world like? What are the prevailing surface ocean temperatures like? What are subsurface ocean temperatures like? Do icecaps already exist at the poles? How quickly does temperature drop per 1,000 feet? How high are those mountains of yours? Are there magical areas of heat and cold, wet or dry?
Edena_of_Neith
