Engine (shock) cooling what's the deal
Last night I decided to climb up from my strip at 250 above MSL to 4000 to practice some stalls and minimum controllable airspeed etc, within a 4 miles radius above my strip, the temp at the field was about 12C on my departure at about 7pm, during the shallow turning cruise climb the CHT gauge was just over half way in the middle of the green which is where it normally is ( the engine is a lycoming 0360 c4f). Upon initiating my descent and heading back to the strip i noticed a cloud cover moving over at about 1500 to 2000 agl I decided to expedite my decent by basically pulling the power back a bit and pointing the nose down and dropping at about 1100 to 1300 FPM to get in under the approaching cloud cover. Levelling out at about 1200 agl to set up for landing i noticed the CHT was right at the very bottom of the green range which got my attention and I chastised myself for not doing a slower fpm circular decent to avoid such rapid cooling.
I understand that the type of decent I did was a dumb thing to to do even if the CHT never got outside the green arc. My question is that even if it did stay within the green arc can rapidly dropping from normal operating temperature to almost falling out of the bottom of the green operating threshold damage the engine?