Altimeter accuracy X-Lander

Hi...Really need to have a layman's explaination as to the effect of air temp on altimeter accuracy. Page 41 in my book says that the further the temperature varies from "normal" for a given altitude, the less accurate my altitude readings will be.....
What's up with this....????

[Brad]

This is how altimeters work. The pressure of the atmosphere is measured via a barometer. an altimeter simply takes this measurement and applies a calculation to arrive at a value. This value is your altitude. So the higher you are, the less of the atmosphere is on top of you, thus a lower atmospheric pressure. If a cloud comes between you and the atmosphere the cloud takes on the load of the atmosphere dropping the pressure underneath, this will cause your watch or most any altimeter to give you a higher value for your altitude. Weather is funny, it is unpredictable and varies, your watch is much more predictable than the weather. The weather in your area will through the accuracy of your watch off, however it will always do it in the same way. You can monitor the pressure and based off of meteorological knowledge you can guess at what is coming your way.
I hope that helps,