Thanks for the answers.
JVM, how about when the A/C is static...? The effect in WoP/BoP is overdone (I can see what you mean now) but when the A/C is static the rain will have an effect. I was at Hawkinge at the weekend, unfortunately it rained, but I got to see the (repro) Hurricanes outside get wet. It was quite a sight I must say.