What if the Spelljamming Reality existed in the Ground Setting?

[Edena_of_Neith]

I proposed this once and wish to propose it again: Why not use the Spelljammer rules for a specific ground campaign setting?

That is:

In the 2E Spelljammer Campaign, any object that left an atmosphere took a small amount of that atmosphere with it. The larger the object, the more atmosphere it took (but never enough to make any dint in a planet's actual atmosphere.)
What if this rule was applied to the surface terrain itself, and we counted mountains as rising out of the atmosphere ... and thus taking atmosphere up with them?

Under this system, atmospheric pressure would not drop with altitude IF the rise involved a mountain range or plateau (such as Tibet or the Great Basin are plateaus.) Instead, the atmosphere (indeed, the whole troposphere) would 'curve' up and over and down the mountain range and/or plateau in question.
Surface winds and weather phenomena, jet stream winds, clouds, storms, and the boundary of the tropopause itself would 'curve' upward to match the change in surface altitude, rising up and over mountain ranges, and up and across and over plateaus.

Atmosphere pressure would still drop normally above level land. Above mountains and sloped terrain of any kind, altitude would be 'straight up' from the point of view of the ground: if the ground was rising straight up (as per a cliff) then 'straight up' in altitude would be sideways (thus, the atmosphere 5 miles *sideways* from a steep mountain would be thin, as opposed to 5 miles *upward*, until you got to the mountaintop, beyond which atmospheric pressure would drop normally directly above the peak.)

If two 50,000 foot high mountains stood 20 miles apart, and you tried to fly from one to another, atmospheric pressure would drop, you would come to the clouds (which would be rising nearly straight up or down, relative to the mountainside, although rain would still fall normally according to gravity ... this could result in some very strange atmospheric phenomenon) and then to the jet stream winds (again, racing up or down), then to the jet stream again as you 'descended' towards the other mountain, through more clouds and possibly storms, then back to the 'surface' with surface temperatures and pressures. The air temperature would drop from sea level warmth to the frigidity of 100 below zero, then back to the warmth of the surface.

There would be other notable changes with this system. Mountains would no longer block storms, so no rainshadow areas would exist. Mountains would cease blocking the flow of moisture to the Arctic, resulting in violent storms there. Mountains would also cease blocking the flow of cold air, allowing Arctic Air to plunge equatorward in dramatic fashion. As the Ice Queen blew her wintertime gales, and these met up with the Sunlord's heat, colossal storms would blast across the temperate latitudes. Hurricanes would no longer be disrupted by mountains either, although land would still weaken and dissipate them eventually.

In the Forgotten Realms, if this were the system, the entirety of the Realms would become wetter. The whole Unapproachable East would change to forest (subarctic in the north to temperate in the south, except where magic had permanently desertfied the land.) The Shaar would become a temperate forest. All those mountain ranges would become green and fertile, the ice and glaciers disappearing.
It would become colder in the winter further south, and warmer in the summer farther north. The Frozenfar would be assaulted by heat waves and rain and begin to melt rapidly, while the Shining South would see freezes and snow during the winter (much to Dambrath's delight and Var the Golden's consternation.) The Inner Sea would grow, the Great Glacier would expand faster (magic, anyone, to stop it?), and Anauroch would see the usual (rain, which mysteriously and instantaneously dried up.)
Flight of any sort would take on new dimensions and problems, especially around mountains (the rain is blowing upward, did you say? And it's raining up there, and snowing down here? There's a gale from the north here, but it's calm aloft, say you?)

Perhaps the Spelljamming reality only exists in some mountain ranges and plateaus, and has been cancelled by magic (or, never instated by magic) in others. Thus, my mountain range is green and fertile, but yours to my north is barren and airless (but it blocks cold waves, making my mountains even warmer.) Perhaps the plateau at 10,000 feet is barely inhabitable, but that great plateau at 25,000 feet is lush and green.
In cases like this, the prevailing winds and jet streams are wildly altered from the norm as they must deal with the normal reality in some areas, and the Spelljamming reality in others. The entire worldwide climatic system is altered. Temperate latitudes exist at 60 degrees north in some places, but only 30 degrees north in others. The 'Chunnel' of mountains allows cold air to reach the equator in one section of the world, producing snow there, compliments of the Snow Queen. However, the Sunlord created another passage for his heat waves, and part of the Arctic is tropical.

 

[Torm]

You, my friend, have quite thoroughly illustrated "too much time on one's hands."

And so have I, as I have read the whole thing.

That said, interesting concept. Particularly some of the side effects on some spells.....

 

[Edena_of_Neith]

How would you handle it in your own campaign, Torm?

 

[Nyaricus]

That's pretty frickin cool. Makes me think that someday, we humans will find another planet like this in RL.

cheers,
--N

 

[Angel Tarragon]

:\ I think I have a bit of a headache now.

 

[Edena_of_Neith]

The atmosphere, mountains, and gravity

If the atmosphere rises up and over mountains and plateaus, there is a simple way to handle the atmosphere: assume the atmosphere begins gradually 'rising' long before a mountain range is reached, so that when the range is reached the topmost peak of that range serves as a point of atmospheric pressure at sea level equivalent. Lower down the mountain and at low altitudes all around, atmospheric pressure is actually higher than sea level (but only barely: there is no steep increase in pressure, not even at the base of 50,000 foot mountains.)
Gravity, in this case, operates normally. Cloud heights, storm heights, cloudtop heights, and jet stream heights gradually rise as one approaches the mountains, going up with the rising level of sea level pressure (this could cause a lot of problems with dry lightning and virga in general.)

Or ...

Gravity pulls one down, relative to the way one is standing, anywhere on the planet.
Thus, on a sheer mountain side, up is OUTWARD. Houses, trees, and crops thrust sideways out of the cliff. People walk up and down the cliff normally (gee dad, why is half the sky filled with land?) (gee, dad, a thunderstorm came *down* upon us, from the west, yesterday. Today, one is coming *up* at us from *below* the mountain, from the east.) (gee, dad, the sun rises in the morning overhead, and sets when it's hottest at what the surface people call midday.)
Likewise, clouds, winds, and anything else *up* such as birds, move up and down. The very jet stream itself (the high altitude winds) blows up, over, and down, relative to the mountain.
In very large caves and where great overhangs exist, gravity allows one to walk on the ceiling and walls (the drow and illithid love this, naturally.) If the cave is large enough, 'clouds' can form in the middle of it, and it could even rain (all ways.)

In this second scenario, a resolution must be made. How far 'up' can someone on the side of the mountain go, before he is 'up' relative to the flat ground around the mountain, and subject to normal gravity?
The answer to that is that the gravity well varies drastically with terrain, and there is no good answer to the question, close to the ground. What is 'up' over here, may be 'sideways' over there, pointed 'left' yonder, and 'right' further yonder. Higher up, a more gradual change occurs regarding what is 'up' (which the clouds, jet stream winds, tropopause, and stratosphere, etc. follow) but nevertheless a person could accidentally pass from one 'zone' to another gravity 'zone' by mistake.
If this is the situation, strange wind eddies and turbulence occurs near the ground, as the surface winds react to the constant changes in gravity. Sudden windstorms, changes in wind direction, whirlwinds, and odd phenomenon occur. Tornadoes are even more freakish than their usual destructive selves. Snowstorms are a strange delight, as the snow falls in all different directions. Rain is even stranger, and pools form in bizarre spots where gravity all bends to that point (hey dad, look at the upside down lake.)

In this second scenario, a great tower might stand beautiful and majestic on a mountain peak.
All around this tower, pointed nearly sideways, is the fortress guarding the tower, with walls pointed almost straight outward. Walking the outer wall allows you to walk all the way around the mountain.
Below this, the city sweeps down the mountainside, some buildings pointing up, some sideways, and a few downward from underhangs. Trees and brush mimic the buildings. No rockslides (or normal erosion) exists, streams meander gently down sheer cliffs (or flow backwards up underhanging cliffs) and placid lakes stare out across the distant surface geography.

The primary thing of note in this scenario is the conflict in the lower atmosphere, below the cloud level.
If I am standing sideways at point A, and you are standing upright at point B, and point C is above us both, gravity is not pulling both ways from point C towards me and you (hopefully!) Yet, gravity wants to do just that, since 'up' is a mere state of reference, depending on how the ground slopes.
Since the atmosphere IS affected by gravity, strange things are going to be the norm, as the 'points of reference' compete with each other for dominance (will gravity be determined from point A? Point B? Somewhere else? Or will it shift back and forth?)
All flying creatures, all missile weapons, all thrown and catapulted items, are subject to the push and pull of competing gravity reference points.

Perhaps a really big mountain is facing a small mountain. Everything falls 'up' towards both mountains. But the point in between where falling reverses might be close to the small mountain, because the big mountain has more 'strength' of force to enact it's gravity. Or perhaps the line of demarcation varies (though it stays closer to the small mountain.) Or perhaps the cloud giants have used their magic to completely overthrow the small mountain's effect (everything on the small mountain falls towards the big mountain unless tied down, and the mountain itself is trying to tear free of it's moorings.)
This effect could occur in microcosm. A big house might affect gravity more than a small house. A big tree might win over a small tree. A large embedded rock wins over a small embedded rock (maybe pulling it out of the ground.) An embedded LIVING BEING would affect this gravitational tug of war, so the cloud giant who embedded himself in the ground would overwhelm the gravitational pull of the small rocky outcropping the party is standing on, causing them to all fall (because what was 'up' for the party changed just enough to unbalance them.)
Creatures and objects not somehow attached or embedded in the ground would not affect the gravity. Air would never affect it; air would only be affected by it.