You said “The centers of most bigger continents will be dry (yellow), coast regions will be mostly humid (green) and continental areas lying east of a big stretch of water will be very humid (dark green).”

But if I understand the algorithm, it would create a map where continental areas lying west of water would be very dry.

I used a very simple algorithm that goes somewhat like this (pseudo code, no warrenties the sample values will work):

startContingent = 64
diffOverLand = -2
diffOverWater = 4

for (y from 0 to map.height)
{
    contingent = startContingent
    for (x from 0 to map.width)
    {
        if (IsLand(x,y) == true)
            contingent += diffOverLand
        else
            contingent += diffOverWater
         humiditymap[x][y] = contingent 
     }
}

</pre>
    

The parameters like startContingent, diffOverWater and diffOverLand can be set in each of our map-creator project. So, depending on how you play with them the map becomes anything from very dry to very humid.

This model does produces results that look ok but cannot be used as a model for real-world weather or vegetation simulation.  

Afterall, it's just a way to get decent looking maps for a game.

Did that anwer your question?

Cheers,
Manuel