This week's tip is from Understanding the Sky by Dennis Pagen

Old clouds don't die, they just fade away.

This disappearing act has special significance for soaring pilots, for one trick we pilots use is to fly under active clouds and ride the thermal updrafts to new heights, new horizons.

For this reason it is important to be able to distinguish newer clouds from older clouds.

A fading cloud is a drying cloud. In this drying process the small particles disappear first.

This can change the appearance of the cloud, for different size particles reflect light differently.

Generally an older cloud will take on a duller or more yellowish hue compared with a new cloud. This is a subtle difference but one that can be detected with practice.

Also, older clouds tend to be softer at the edges than the younger, clearly defined clouds.