Saturday, December 1, 2012

Climate in Alphatia

While developing the realms of Alphatia, it seemed that a clear sense of relative weather conditions on the isle-continent was missing.  Having nearly completed the series on Foresthome, I felt I should take a break and focus on this topic.  Not being a scientist or even remotely acquainted with the mechanics of climatology, I relied on various Earth maps as rough guidelines.  Since Mystara is inspired from Earth’s prehistory, this approach seemed to make sense.  On the other hand, Mystara is a fantasy world, partly governed by magic and immortal fiat as the rationale for some of its improbable weather patterns.  Suggested climates may also reflect pre-existing designs rather than scientific logic.  This article isn’t meant to change any of the latter (at least substantially), neither is it the last word on the subject.  It remains open for debate, and its contents can (and probably will) be altered over time.


Earth Global Winds
Mystara’s prevailing wind directions match those on real Earth.  In the northern hemisphere between the equator and the northern tropic, trade winds blow toward the southwest.  North of the tropic, winds blow toward the northeast.  Along the equator and the 51st parallel (northern Europe), these winds pick up moisture, which generates more precipitation.  Along both tropics, however, dry air tends to keep the land below arid or semi-arid.  In the northern hemisphere, this is the latitude of the Yazak Steppes, Sind’s desert, the Emirates of Ylaruam, and the southern Isle of Dawn.  Alphatian winds blow predominantly toward the northeast.

The diagram below gives a general idea which way sea currents might be flowing.  Just north and south of the equator, waters are likely to move westward.  Mystara does not have an ocean equivalent to Earth’s Atlantic.  In its place lie a series of islands, including Alphatia, surrounded by relatively shallow seas.  The area around Alphatia still is befuddling as regards local sea currents.  The Coriolis effect that would normally cause warm waters to gyrate clockwise probably does not apply in this region.  Polar currents are likely flowing southward.  Warm equatorial currents are pushing northward.  The problem around Alphatia resides in three bottlenecks through which moving waters are channeled.

Jurassic sea currents
Following a pattern similar to real Earth, polar currents might flow down the east coast of Alphatia, reaching warmer waters south of Bellissaria.  On the other hand, currents also continue upward along its west coast, funneling slightly warmer waters.  Part of this flow finds its way around the Isle of Dawn’s northern tip, and south from there toward the Sea of Dread.  Currents around Alphatia are likely weak, except through bottlenecks such as Bellissaria’s Strait of Minaea, the Strait of Dawn around Greenspur, and the Strait of Helskir by the Isle of Dawn’s northern tip.

This contradicts a map published in the AC1010 Almanac, which shows a sea current heading north along the Isle of Dawn’s western coast.  This is debatable and I’m not sold on either version.  The trouble with a northward flow is that it seems to conflict with the Sea of Dread’s natural clockwise movement.  A southward flow looks equally strange, with a northbound current near Alphatia reversing itself to stream through the Strait of Helskir.  One may assume magic is somehow involved here—visions cross my mind of gargantuan koprus cursed for all eternity to flip their tails and fan sea currents. ::cringe::

Mystara winds sea currents map


A cold sea current affects Alphatia’s northeastern coast, while a relatively warmer one rounds its southwestern shores.  The expectation is that its oriental side would therefore be cooler.  A low pressure trough is likely to bulge deep from the north especially in the winter, inferring that much of Alphatia’s upper half would often be overcast during that season.  The far north would therefore be cool and moist, often foggy, as with real Earth’s northern Scotland.  The southern end, being very close to the 31st parallel, would be much drier.  The bottom edge of the map shown below is the 31st parallel (northern tropic) .


Predominant winds blow from the southwest.  Some moisture would likely come from the Sea of Dawn, hitting the Kerothar Mountains.  In other words, Alphatia’s west coast would have ample rain.  Logically, a semi-arid band should exist on the eastern side of the Kerothar Mountains, since they would trap most of the sea’s moisture.  Pre-existing designs of Alphatia show instead two huge forests in that region—the Shiye Lawr and Blackheart.  We’ll have to assume that magic is used there to counteract the region’s natural aridity.  Winds would also pick up moisture in the Aaslan Gulf, showering its northern shores in winter.  This region is home to the huge swamps in Haven and Vertiloch.  South from there, a more Mediterranean climate might prevail, being close to the band of dry weather near the 31st parallel.  Winds blowing in that area pick up little moisture from the Strait of Dawn, causing meridional Alphatia to remain drier than the rest.

Mystara Alphatia Climate Map
Here are actual real-Earth climate definitions:

Tropical Wet: includes rain forests and is characterized by rainfall at least  1,750 mm (69”) per year. Mean monthly temperatures exceed 18°C/64°F during all months of the year.  Seasonal monsoon winds prevail for several months, bringing the rainy season.  Regions within North America, South America, Sub-Saharan Africa, Australia and East Asia are monsoon regimes.

Tropical Wet & Dry: includes tropical savanna in semiarid to semi-humid climate at subtropical and tropical latitudes, with average temperatures at or above 18°C/64°F year round and rainfall between 750 mm (30”) and 1,270 mm (50”) annually. This climate is widespread on Africa, and is found in India, northern parts of South America, Malaysia, and Australia.

Semi-Arid: describes dry regions including scrubland and steppes most commonly found around the fringes of subtropical deserts.  Hot semi-arid climates tend to be located in the tropics and subtropics, with sometimes extremely hot summers and mild to warm winters. Snow rarely (if ever) falls in these regions.  Cold semi-arid climates tend to be located in temperate zones, typically in continental interiors some distance from large bodies of water.  Cold semi-arid climates usually feature hot and dry summers, and cold winters with some snowfall. They tend to have higher elevations and are sometimes subject to major temperature swings between day and night, as much as 13°C/23°F.

Arid: describes the driest regions. Deserts usually have a large diurnal and seasonal temperature range, with hi/lo temperatures depending on location (in summer up to 45°C/113°F, and low nighttime temperatures in winter down to 0°C/32°F).

Mediterranean: is a sub-tropical climate typically found near large bodies of water such as the Mediterranean Basin, most of California, West and South Australia, southwestern South Africa, and central Chile. It is characterized by hot, dry summers and cool, wet winters.  This climate’s temperatures are generally moderate, with a comparatively small range between the winter low and summer high.  It tends to be on the west side of continents.

Humid Subtropical: this climate zone features winter rainfall (and sometimes snowfall) associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones.  Humid subtropical climates lie on the east side of continents, roughly between latitudes 20° and 40° degrees away from the equator.

Earth Climate Zones Map
Marine West Coast: oceanic climate is typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia.  It is accompanied by plentiful precipitation year round, with cool/temperate weather such as in Northern Europe, North America's northern west coast, etc.

Humid Continental: this climate is marked by variable weather patterns and a large seasonal temperature variance.  Places with more than three months of average daily temperatures above 10°C/50°F and a coldest month temperature below −3°C/27°F and which do not meet the criteria for an arid or semiarid climate, are classified as continental.

Sub-Arctic: describes a region with little precipitation and monthly temperatures above 10°C/50°F for 1-3 months of the year, with permafrost in large parts of the area.  Winters include up to six months of temperatures averaging below 0°C/32°F.  It includes taiga type terrain with boreal forests consisting mostly of pines, spruces, and larches.

Tundra: in this climate, one month is warm enough to melt snow, with a year round average temperature never more than 10°C/50°F, and extremely cold winters.  Tundra climates as a rule are hostile to woody vegetation even where winters are comparatively mild by polar standards, as in Iceland.  Rainfall and snowfall are generally slight, but swamps and bogs are the norm.



From a humorous angle, here is a suggested listing of Alphatian cities and their (very approximate) real Earth equivalents.  Temperature ranges shown below reflect winter and summer averages.  Temperatures for cities on Alphatia’s northeast side were decreased 1-3°C/2-5°F to reflect the Sea of Esterhold’s colder current (relative to the US eastern seaboard).  Figures listed below have been altered accordingly.

1. Farend, Qeodhar: Trondheim, Norway –9°C/16°F—16°C/60°F (oceanic)

2. Trollhattan, Limn: Glasgow, UK. 2°C/36°F—20°C/68°F (oceanic)

3. Draco, Stonewall: Seattle, USA 2°C/36°F—24°C/76°F (oceanic)

4. Denwarf-Hurgon, Stoutfellow: Zürich, Switzerland –4°C/28°F—24°C/79°F (oceanic/alpine)

5. Asla, Haven: San Francisco CA 8°C/46°F—22°C/72°F (Mediterranean)

6. Sundsvall, Vertiloch: Sofia, Bulgaria –1°C/30°F—28°C/82°F (humid continental)

7. Errolyn, Theranderol: Belgrade, Serbia –1°C/30°F—29°C/84°F (humid subtropical/humid continental)

8. Eagret, Greenspur: Los Angeles, USA 10°C/50°F—29°C/84°F (Mediterranean)

9. Bluenose, Arogansa: Palermo, Italy 8°C/46°F—29°C/84°F (Mediterranean)

10. Archport, Eadrin: San Diego, USA 9°C/48°F—25°C/77°F (Mediterranean)

11. Rardish, S. Randel: Sydney, Australia 8°C/46°F—26°C/79°F (humid subtropical)

12. Dmiliburg, N. Randel: New York City, USA –6°C/21°F—26°C/79 (humid continental)

13. Sabetta, S. Bettellyn: Colorado Springs, USA –1°C/30°F—28°C/82°F (continental semi-arid)

14. Weitara, NE. Bettellyn: Boston, USA –8°C/18°F—25°C/77°F (humid continental)

15. Citadel, N. Bettellyn: Cleveland, USA –7°C/19°F—27°C/81 (humid continental)

16. Alfleish, Shiye-Lawr: Budapest, Hungary –4°C/25°F—27°C/81°F (humid continental)

17. Tirenios, Central Foresthome: Chicago, USA –6°C/21—22°C/72°F (humid continental)

18. Greenwood: E. Foresthome: Montréal, Canada –10°C/14°F—21°C/70°F (humid continental)

19. Haggleby: W. Forestome: Minneapolis, USA –14°C/7°F—29°C/84°F (humid continental)

20. Shraek, Blackheart: Calgary, Canada –5°C/23°F—22°C/72°F (humid continental)

21. Shiell, S. Frisland: Edmonton, Canada –9°C /16°F—18°C/64°F (humid continental), with extremes easily exceeding these numbers

22. Mafertat, N. Frisland:
Stockholm, Sweden –8°C/17°F—19°C/66°F (humid continental)

23. Skyreach, Floating Ar:
Uppsala, Sweden –10°C/14°F—19°C/66°F (humid continental)

24. Starpoint, Ambur: Oslo, Norway –5°C/23°F—18°C/64°F (humid continental)



For adventuring purposes, it is important to know how latitude affects daylight.  For example, in real Earth Trondheim (a bit above the latitude for Qeodhar in Alphatia) the sun rises in the summer at 03:00 and sets at 23:40, but stays just below the horizon—under cloud-free conditions, there is no darkness and no need for artificial lighting outdoors from 23 May to 19 July.  In winter, the sun rises at 10:00, stays very low above the horizon, and sets at 14:30.  At the level of Starpoint, daylight varies from more than 18 hours in midsummer to around 6 hours in midwinter.

Mystara features two large openings at the poles instead of ice caps.  These lead to the Hollow World.  The region at the rim, which neither Mystara’s sun nor the Hollow World’s own internal sun can reach, is anti-magic and remains permanently dark.  Violent storms blow across this deadly frozen world, making exploration nearly impossible.  Monsters that have adapted to these conditions survive there, compounding difficulties.


Special thanks to Dean Gilbert, Richard T. Balsey, D. J. Hartel, and Janet Deaver-Pack for their contributions.