Topic: Temperature and Latitude

[Skaran]

Just wondering; for determining weather the charts in RMSS Gamemaster Law you have a set of charts for base temperatures (page 124-125), should there have been a modifier for latitude for these charts? Otherwise wouldn't the worlds poles and equator have the same temperature ranges? Thoughts, is there a missing bit?

[tulgurth]

Just wondering; for determining weather the charts in RMSS Gamemaster Law you have a set of charts for base temperatures (page 124-125), should there have been a modifier for latitude for these charts? Otherwise wouldn't the worlds poles and equator have the same temperature ranges? Thoughts, is there a missing bit?

I honestly believe that ICE missed something in the creation of that part of the GM Law.  You see modifiers for everything but location away from the 40th parallel, where all data is assumed for an earth like planet.

In another source I have found some information based on the 40th parallel for a known gaming world (Out of respect for ICE, I will not name the gaming world as it is not produced by ICE, or ever has been produced by ICE).  These rules basically state:

For every degree of latitude one travels in a North-South direction, the Temperature will receive a +/- 2 degrees change in temperature.  For instance if you were to travel 3 degree North of the 40th parallel, the average temperatures will be 6 degree Fahrenheit cooler.  However, if one was to travel 3 degrees South of the 40th parallel, the average temperature will experience a shift of 6 degrees Fahrenheit warmer.

[jdale]

Based on http://commons.wikimedia.org/wiki/File:Annual_Average_Temperature_Map.jpg
I think +/-1 degree F per degree north/south is a better fit. The image shows about 30 degrees F difference between ~40 degrees North and the equator, and about 50 degrees F difference between ~40 degrees north and the north pole. Antarctica is colder, but the elevation covers that (http://basementgeographer.com/wp-content/uploads/2010/09/420antarctica-420x0.jpg labeled in meters).

[PhillipAEllis]

There is one problem with the known gaming world, though: as you move closer to the equator, the temperature range decreases while the baseline temperature increases, while the range increases towards the pole, but the base temperature decreases. In the real world, in summer the city of Melbourne is usually colder than Brisbane, but its maximum in summer is greater, while year-round the temperature average & range in Brisbane is steadier, with less variation (the winters, for example, are warmer, more temperate). There are also variations such as dry & wet seasons towards the tropics, mainly steady rain at the tropics, etcetera.

[jdale]

Is that captured by the terrain modifiers? E.g. deserts have +10 during the day and -10 at night.

There is an effect regarding seasons, that the equator has much less seasonal variation than the poles. You could add or subtract a variability class for each X degrees north or south. Not sure what X would equal.

[Skaran]

In various versions of the game of Traveller the worlds were split into hex rows numbered 1-11, the equator was on row 1 and there were 10 rows above and below this. Latitude effects were set at 0 for hex row 4 and then for an Earth sized world + or - 7 degrees celcius were applied adding to rows numbered lower than 4, so hex row 3 for example had +7 row 2 +14. Hex row 5 -7 etc. The poles were in hex row 11. Other effects were modified by axial tilt and eccentricity. But the + or - 7 degrees celcius per hex row which would be roughly 9 degrees of latitude seems OK, now how many degrees Fahrenheit would a 1 celcius degree adjustment be?
For the country I am working on at the moment its approximate latitude is 24 degrees North primarily wooded and located on a coast.

[jdale]

+7 Celsius = +12.6 Fahrenheit

[tulgurth]

In various versions of the game of Traveller the worlds were split into hex rows numbered 1-11, the equator was on row 1 and there were 10 rows above and below this. Latitude effects were set at 0 for hex row 4 and then for an Earth sized world + or - 7 degrees celcius were applied adding to rows numbered lower than 4, so hex row 3 for example had +7 row 2 +14. Hex row 5 -7 etc. The poles were in hex row 11. Other effects were modified by axial tilt and eccentricity. But the + or - 7 degrees celcius per hex row which would be roughly 9 degrees of latitude seems OK, now how many degrees Fahrenheit would a 1 celcius degree adjustment be?
For the country I am working on at the moment its approximate latitude is 24 degrees North primarily wooded and located on a coast.

OK 1st things first, the temp conversion for Celcius to Fahrenheit:

   (Celsius Temp + 32) * (9/5) = Fahrenheit Temp [just in case you do not know the conversion rate]

Now as far as the latitude being 24 degrees North of the equator (If it were me, since you got 2 different opinions here:

Since it is based on 40 degrees North of the equator and you are only 24 degrees North of the equator it would be

2(40 - 24) + Avg Temp for the month = New avg.

So if you were using the guidelines set forth in GM Law, and assuming the 4th month of the year, or 1st month of spring:

The First month of Spring has an avg Temp of 46 degrees F.  Since we are 16 degrees south of the 40th parallel, we would add 32 degrees to the temp or have an average of 78 degrees F.  Then you would add the modifiers for Coastal area, +5 for high temp and -5 for low temp.  Since you said wooded I am assuming Forest and not jungle.  This would give a -5 modifier to the high and low temps so your overall modifiers would +0 for the high and -10 for the low.  Then you would roll your Open ended dice as normal to get your adjusted temps for the day.  To convert into Celsius, use the formula:

(Fahrenheit Temp - 32) * (5/9) = Celsius Temp

[Skaran]

Doesn't the presence of the water on theCoastal and Sea regions moderate temperature rather than increase it? In which case the cold should get the +modifier and the hot the -modifier?

I did not know you could apply multiple modifiers like those for Forested and Coastal to the same area. Something else left out of the description on how to use the charts!

Incidently hex row 4 on the Traveller chart would contain the 40 degree latitude point if you converted from Travellers celcius system to RMs Fahrenheit you could get a chart which covered the whole planet for base temperatures - you would then just have to adjust for Terrain.

[Wolfhound]

Doesn't the presence of the water on theCoastal and Sea regions moderate temperature rather than increase it? In which case the cold should get the +modifier and the hot the -modifier?

Yes, it can make a HUGE difference. 

For example, I'm in Michigan, where the Great Lakes have very large effects on weather (both temperature and precipitation).  I grew up in northern-lower Michigan, but also lived in Minnesota's Twin cities area for a couple of years.  The Twin Cities were a LOT colder but a LOT less snowy.  The high temps sometimes would be far lower for more than a week straight than the lows that you would likely ever see in the same distance north in Michigan (~45° north), while the the snow around the Twin Cities was usually in the 40-80 inch range if memory serves me correctly; whereas in Michigan where the frigid air coming across the Dakota's, Minnesota and Wisconsin would hit Lakes Michigan (or Superior if you were even further north) and warm up substantially but in the process would evaporate huge quantities of water (it is this evaporation that actually causes the bulk of the heat transfer) and then dump much of that moisture on Michigan, thus resulting in 120-180 inches of snow in the winter (typical range, although it can vary a lot more) but our temperatures are typically 15 to 40°F higher at the same distance north (again with the difference sometimes being much larger).  Likewise in Northern Minnesota, they don't see that much more snow than the Twin Cities area (a little more, but probably not more than a foot or two difference typically), whereas the Keweenaw peninsula of Michigan's western Upper Peninsula, typically sees snowfalls of between 180 and 300 inches per winter (again with the overall range being much wider, their all-time low was >81" in 1930-31 and their all time high was >390" (>32 feet or almost 10 meters) in 1978-79).  This is the same reason that the heaviest snow fall areas in the U.S. (outside of high mountain elevations) are southern Alaska, northern Michigan, southern Ontario, and western New York, but at the same time these areas tend to have mild temperatures as compared to other areas the same distance north.

Likewise, the "Northwest" (Seattle/Vancouver area) is much warmer than northern Michigan/southern Ontario (and thus rarely sees very much snow, but lots of rain as they have even more moisture), and WAY warmer than the northern Great Plains.  And likewise the high's are much lower when down-wind of large bodies of water.

[Skaran]

So that would mean then that the cold and warm modifiers as applied to Coastal and Sea should have clarified which tables they applied to. So Cold should apply to the High Temperature Chart and Warm to the Low Temperature Chart to reflect moderation due to the large bodies of water.

[Jacinto Pat]

It might just be best to can the charts and find a "similar" real city and use their weather.  Moderating effects of large bodies of water (continental vs. maritime), altitude, latitude, presence of warm vs. cold currents (think temperatures in S. England receiving the Gulf Stream vs. same latitude in the US on either coast), blocking/funneling effects of mountains (Alamosa in CO was -8 F for a high while higher altitudes 50 miles away but out of the San Luis Valley were  +40 F a few days ago) all make it hard to capture in a simple to use chart.