Following is a quote from the developers:
Let’s move swiftly along to the subject of today’s dev diary, the
weather system.
With Johan away to E3 we didn’t want to leave you all with a total
information blackout so I have been drafted to fill the breach on the
dev diary front. For those of you who have no idea who I am, I am Chris
King and I am one of the designers of Hearts of Iron 3.
Let’s move swiftly along to the subject of today’s dev diary, the
weather system. If you look at weather forecasting organisations, they
use huge super computers to try and predict the weather and have been
known to be slightly wrong on occasion. A highly detailed exact weather
model was going to be beyond us, but that didn’t mean we couldn’t
improve on our current province based, roll a dice model.
So we went off and spent a couple of days becomes experts in
Meteorology (feel the power of the Wikipedia!) and began to build up
our weather model. The Weather in a province is constructed from three
basic building blocks, pressure temperature and humidity. Pressure and
Temperature are province based properties. We actually have a mean
temperature map, this is then modified by time of year to give a
desired temperature for the province, it further fluctuates around this
based on local factors. Pressure works in a similar way, but we will
come back to it later. Humidity rises over things like water
(especially during high temperatures) and then falls when it rains.
So far pretty basic stuff. However this allows us to create two further
parts to our weather system, the overhead and ground conditions. As
humidity rises and/or temperature falls the overhead conditions will
change from clear to overcast and then to rain. If it is cold then you
get snow. If the winds are high and it is raining you get a storm and
if it is snowing a blizzard. While on the ground if it is cold then you
get Frozen Conditions. If it is raining enough or if the ground has
ceased to be frozen you have a chance of Mud (modified by local
infrastructure).
So far so good, but we could of done all of this with a simple province
based system and odds. However this is where air pressure and a bit of
research comes in useful. If you take Western Europe as an example, low
pressure appears around Iceland and moves east. There is a permanent
area of high pressure centred around the Azores which pushes the low
pressure systems along their familiar track. Hearts of Iron 3 is very
similar in this regard. The area around the Azores is defined as high
pressure which radiates out, while Iceland will generate low pressure
that tracks into Europe and is repelled by areas of high pressure. Low
pressure systems pickup their local weather and move it in weather
fronts. What you end up with is bands of weather moving around the
globe bringing things like rain and snow.
Now as I said at the top of this dairy a precise weather system is
going to be beyond us, but it doesn’t mean we can’t create a system
with a nice touch of reality. In our case you will be able to see the
weather fronts moving and this feeds into to your strategy. You are
thinking about invading France as Germany, but when? Well it is raining
over Germany at the moment, but you can see that the weather coming out
of the west is clear. The answer is soon.
To show the shocking outcomes that our new weather system produces, here are some screenshots of rain coming to Scotland.
