Ion storm formulas are probably among the least known in the Planets community. So, like others sat down to reveal the exact population growth rules, I did my best to find out the Storm formulas for Tim's host. And because many people until now requested them, I decided to write them down here. Enjoy!
This article was first published in October 2000, and updated a few times inbetween.
Ion storms are circular subspace disturbances that move rather randomly through the Cluster and affect ships. They are characterized by a position, heading (specified in degrees, like ship headings), voltage (strength of the storm, measured in MeV), and a radius (size of the disturbance in light years); and a storm can be either growing or weakening.
Growing storms always have odd voltages, weakening ones have even voltages. This means that adding one to the voltage changes the storm's status.
Ion storms are grouped in classes, depending on their strength (voltage):
The speed of the storm is determined using the first matching rule of the following:
The storm now moves, using the heading reported in the Ion Advisory messages, and the usual movement rules (travelled way = square of Warp).
The heading for the storm to take next turn is random, between +10 and -10 degrees from the current heading. The new heading is reported to players. The reported Warp speed is worthless, at least for the third category above: it will change until the storm moves next time.
All storms start as growing storms, with an odd voltage. Each
turn, the voltage increases by a random amount between 0 and 10
MeV (in steps of 2). The radius decreases by 0..3 ly. If a storm's
radius gets negative, the storm gets weakening by receiving one extra
MeV; the new radius is then
Growing storms may turn in to weakening ones. This is done by increasing their voltage by one. The chances for doing so are, in each turn
Note that each storm gets all applying chances in series, so it can happen that a 400 MeV storm increases by 2 MeV because it ``won'' both the 1% and the 2.5% chance.
Each turn, the voltage is reduced by 4 to 14 MeV, in steps of 2. Should the voltage drop to zero or less, the storm disappears.
The documentation describes the pancaking effect. This happens at a chance of 3.33% per turn: pancaking storms have their radius doubled, and their new voltage is the square root of the original voltage.
The storm size increases by a random amount between 0 and 10 ly each turn, after the above effects happened.
If two storms come close enough, they merge into one. If two
storms are close enough for this is determined by the following
In addition, one of the storms must be stronger than the other (greater voltage); two storms of equal power do not merge.
Once we know that two storms merge, we have to compute the new
position and size of the storm. It will keep the same Id number,
warp factor and heading like the stronger of the two storms.
The new center lies on the line between the two original centers,
The new voltage of the storm is (voltage of stronger storm) + sqrt(voltage of weaker storm) (with sqrt = square root), likewise for the new radius (radius of stronger storm) + sqrt(voltage of weaker storm). From these equations, it follows implicitly whether the new storm grows or weakens.
Merging of storms happens after movement, but before the ship effects and before generation of new storms.
Ion storms affect ships. All ion storms, no matter how weak, de-cloak ships. Only the advanced cloakers are safe from this.
Storms with 150 MeV or more affect uncloaked ships. That is, only advanced cloakers can safely travel through such an ion storm -- cloaked.
Ships are affected if they're inside the storm after the storm moved, but before they moved themselves (all Ion storm related things are quite early in the host order).
Note that the Ship_Mass seems to be the mass of the ship at the beginning of the turn, that is, the same as it was in your last RST. So load your ships with cargo early, not in the same turn you enter the storm.
Ships in an ion storm get experience. Roughly, you get one experience point for every 20 MeV the storm has more than 140 MeV.
The actual formula is
Ship experience is mentioned in the original documentation, but due to the fact that it's normally kept secret, the experience rules are close to unknown.
Storms outside the range (0,0)-(4000,4000) disappear the turn after they moved there. It is possible (though not very likely) to have storms at coordinates usually considered invalid: I already had a storm with a negative X.
If there are more storms than the Host Configuration allows, the weakest ones disappear.
Newly generated storms may have different warp factors reported (Warp 5 and Warp 7 are not possible according to the above rules). However, reported warp factors are worthless anyway as Host re-computes them before actual storm movement. Up to three new storms can be born per turn.
When I say random value between A and B, the border cases are less likely than the others due to rounding effects.
New ion storms do not appear completely random, but they follow certain rules.
PHost 4 contains Ion Storms modelled after this analysis.
This information is by no means official. It is believed to be mostly correct, but may still contain off-by-one errors or worse. I have not run extensive test games to verify it.