CT Only: What's It Like Outside?

[Timerover51]

Yes, local weather depends on a LOT of factors:

Fixed quantities:

• Stellar class and luminosity type.

• Orbital radius and eccentricity.

• Albedo and axial tilt.

• World size, atmosphere type, hydrographics

Variable quantities:

• Terrain type, winds, and humidity.

• Latitude, altitude, and season.

I'm not looking for a doctoral dissertation on meteorology; just something that produces a basic table from the Fixed quantities for any given world, to which the Variable quantities can be applied to derive DMs to a few simple die rolls.

If there is nothing "out there", then I'll have to build one for myself.

The following paragraph comes from Double Adventure 2: Mission on Mithril, designed by Marc Miller. I think that is about as canonical as you can get.

TEMPERATURE AND WEATHER

Mithril is a wild, cold planet with a violent climate. The average daily temperature is blow zero centigrade (below freezing), and fluctuates to lows of thirty below. Weather can be classified as clear, overcast, mild storm, and violent storm. The specific details of temperature and weather can be determined in two different ways. Formulae are presented to allow computation using dice or randomizers; or the tables of pre-generated statistics may be used for ease of play. In either case, the information is then relayed to the players in the same way: in the weather phase of the procedure

Now, this is for a cold weather planet. However, it does give a basis for working up weather in other climates, by changing the average temperature for the area that you are in. Basically, if you use the formulae, then you are using a die roll to raise or lower the temperature. Then, after determining the change in temperature, you go to the weather table, and make another die roll to determine what it is doing out. The adventure also has a pre-generated table of weather changes as an alternative to die rolling.

If you do not have Mission on Mithril, then I would recommend going to DriveThru and buying a digital copy. It will save you a lot of work.

I have always viewed this as a reasonable way to determine weather if you are going to use die rolls. It is designed for easy game use, which is what is needed. Marc did a good job putting this together.

 

[Kilgs]

I guess with gravity, most just use the standard numbers given in Traveller per Size of the world rather than rolling up the world's core and working out actual gravity?

For this and other things (temperature), I like to punch them up in Astrosynthesis to get an idea. But it's too hard to get it perfect so mostly just winging it to get ideas.

Oops

My question is: Has there been any canonical method of determining local weather on a day-to-day basis for any given planet?

Thank you.

Just saw this now... I think World Tamer's Handbook has tables for it. But it may have been mainly temperature based.

 

[kilemall]

Hmm, guess I would start with how much energy and variable temperature occurs.


So closer to star, more heat to work with.


Tidally locked or slow rotation, pretty stable except maybe at the terminus.


More water, more rain/storms, otherwise wind from pressure equalization and Coriolis effect.


Then terrain is more or less likely to get rain based on albedo and temperature and altitude. Quite a bit more rain on seas and coasts.


The thicker the atmosphere the hotter and more violent the storms (greater pressure and thus more energy).


Oh, and for rough G, I would tend to go with atmosphere telling me what the G is- when I brought up this idea before people pointed out about the role of magnetic fields in atmo retention, but I would counter that having a magnetic core increases density and thus mass, lack thereof causes atmo loss and the planet is thus less metal-dense.

 

[Enoki]

Tidally locked planets would have a hot "pole" and a cold "pole" aligned with the star. These two temperature extremes of a very hot and very cold pole would create a continuous and probably fairly violent set of wind conditions between them. You'd have a non-stop set of convection currents between the two points, assuming the atmosphere isn't boiling off at the hot pole and frozen into a solid at the cold...

If it were a slower convection between the two you could get weird stuff like water vapor condensing into clouds or fog as the air cooled and have rainforest-like conditions moving from cold to hot on the returning air.

 

[Ulsyus]

Some of the programs I've recently seen which described exoplanets, such as How the Universe Works, often described planets with horrendous and extreme weather or atmospheric conditions. I do wonder how much my gaming has been influenced by the idea of playing on garden planets, and how I could do a lot more to narrate and use non-permissive outside conditions to the benefit of the plot. To that end I've found the Zozer UWP book pretty handy.

 

[Keklas Rekobah]

Until my copy of WTH comes in, I'll try to normalize the system from Mission on Mithril to an 867 world with an axial tilt between 18 and 27 degrees and an albedo of about 0.3 orbiting a G2-V star at 1 A.U. Then apply DMs for any variations therefrom.

 

[Timerover51]

Until my copy of WTH comes in, I'll try to normalize the system from Mission on Mithril to an 867 world with an axial tilt between 18 and 27 degrees and an albedo of about 0.3 orbiting a G2-V star at 1 A.U. Then apply DMs for any variations therefrom.

Basically, with that world, Mithril would be equivalent to the taiga forest biome, so strips to the north and south of about 55 to 65 degrees or so on Earth.

 

[Whipsnade]

Late to the party here...

There's a free download at DriveThruRPG by Archaic Adventures called the DarkMoore 4 Season Weather Table. You roll a d20 each day and adjust the previous day's weather as directed by a few tables. It handles a different climates like tropical and temperate too.

 

[Keklas Rekobah]

... There's a free download at DriveThruRPG ...

My anti-malware system tells me "The owner of www.drivethrustuff.com has configured their website improperly".

I can wait.

 

[Whipsnade]

My anti-malware system tells me "The owner of www.drivethrustuff.com has configured their website improperly".

The problem is on your end.

DriveThruRPG is part of OneBookShelf and has been around since 2001. OBS operates other download stores for comics, wargames, and fiction. DriveThru is used by Traveller content creators like Gypsy Knights, Stellagama, FFE/GDW, and dozens of other RPG publishers like WOTC, Chaosium, White Wolf, and Sine Nomine to sell their pdfs.

If you want to believe going there will turn your PC into a bot for mining cryptocurrencies that's your call.

I can wait.

Enjoy the wait then. The nine page pdf may be free but I'm not going share it and neither will anyone else.

The grapes were probably sour anyway.

 

[whartung]

You chose the wrong URL. It's not "drivethroughstuff".

Re-bing your googles.

 

[Timerover51]

My anti-malware system tells me "The owner of www.drivethrustuff.com has configured their website improperly".

I can wait.

The correct URL is https://www.drivethrurpg.com//index.php.

 

[Whipsnade]

You chose the wrong URL. It's not "drivethroughstuff".

The "drivethrustuff" address seems to be a gateway or redirect as it brings me to DriveThruRPG on four different browsers.

OneBookShelf started the service as RPGNow so they might have created a few redirect addresses for people who hadn't updated their bookmarks, incorrectly remembered the site's name, and such stuff.

 

[Fovean]

My question is: Has there been any canonical method of determining local weather on a day-to-day basis for any given planet?

Thank you.

To my knowledge, none - on a day to day basis.

But since day to day weather is a concern for your game, you might save yourself some work by building a content generator rather than a weather generator.

So, you know the basics of your planetary environment (Size X, Atmo Y, Hydro Z). Clearly you know what this particular planet is like IN GENERAL.

Describe a baseline season for the action in your game then build a D66 table of variations like “32: An angry thunderstorm blows by a day’s travel ahead; cooler temps today and tomorrow deal with mud and sinkholes” or “51: Micrometeorite storms kick up dust and disrupt radio wavelengths. DM -2 on all comms and sensors checks as well as Drive checks or add 2D hours travel time to circumvent the storm”

Those are coarse examples but you get the idea. Rather than trying to build a realistic table of meteorology you could instead build a table of heroic moments of valor (or of heroic ineptitude) based on local changing weather conditions.

Add in the reactions of the local flora and fauna (if any; if not, colonists will do) to the weather and one roll can be quite significant and build a lot of verisimilitude.

 

[sabredog]

Do you just wing it? Decide with story conditions in mind?

What's your path?

Because worlds will normally have a reasonably wide variety of biomes, even if the world is all water or all frozen, and the players will only be in one tiny spot at a time, I use the story requirements modified by the rough estimate of the world's type to figure it out.

For example, one world frequented by players has a large landmass that runs pretty much longitudinally along the equator with a huge mountainous ridge that divides the north and south. Scattered islands speckle the oceans, mainly in the south. Nearly all the colonists live on end of the main land mass with the starport on the other connected by magrails and sea transport. Most goods run along the magrails, which are huge and largely robotic.

The world tends towards stormy with very rough seas and bad weather patterns from the mountains channeling air currents along the east-west ridges and peaks. So air travel can be rough except far away from those mountains. The place is a young world with an overall feel similar to maybe the Carboniferous Period here on Earth - but no giant bugs or dinosaurs. Oxygen is just a taint in the air requiring filters so you don't irritate your lungs and sinuses. But it does mean it rains a lot south of the mountains with a slightly dryer environment to the north.


So I tell the players when they land and it's become a joke now...."It's raining again on Gehenna."

I have no idea if it really would be like that, but for that world it is the feel I want the players to have of the place. And it means they have to clean their gear a lot or it starts to rot sometimes if they are outdoors a lot. The characters get tired easily there and everything is wet to some degree or another and it causes a constant low-grade annoyance ("Ah jeez, the pocket computer leaked water again and died...we gotta remember to buy local ones to fix that here..."). It all sounds realistic given the way the world is described to have weather like that so it works for me.