Soaring Engine Volume 2
The first volume of the Soaring Engine introduces ridge flying and thermal soaring, outlining simple models of how these forms of lift work and how you might best use them in flat land or mountain flying. This volume leads straight on from where volume one finishes: it describes Convergence and Wave, the other two forms of lift that are commonly used by glider pilots. If you’re an experienced soaring pilot, confident on the ridges and happy whether you are flying in flat terrain or the mountains - then you can dive in here. If you’re less knowledgeable then you should read volume one first.
Both convergence and wave both occur frequently, in most soaring environments. I’ve flown in convergence systems in the heart of Africa, hundreds of miles from the sea, and I’ve climbed in wave in Australia, where the terrain upwind was completely flat for at least a thousand miles. When clearly marked and working well, both wave and convergence systems open up opportunities to fly in straight lines and in constant lift: a recipe for long, fast flights. However both these forms of lift can also be troublesome, especially when they are not marked by clouds. They are much more complex than either straightforward ridge or thermal lift, demanding a deeper understanding of small scale soaring meteorology and an ability to orient oneself in the air, feeling the “signature” of various types of turbulence in different places. Sometimes they can be so weak that they bring no real benefit to the soaring pilot, merely serving to confuse when the anticipated ridge or thermal lift fails to turn up where expected!
To use either wave or convergence systems effectively you need a good understanding of the underlying physical process, visualizing them with simple mental models that can be applied to the current situation. You don’t have to be a meteorologist but you will need a basic idea of how to read a tephigram, an appreciation that air masses can be either stable or unstable, and an understanding of how changing the temperature of a parcel of air will change its density. You’ll also need to know about the dew point of an air mass and how that can be used to predict the formation of cloud. Some of this information is already outlined in volume one and you’ll find more technical explanations in the appendix to this volume.
And a disclaimer: I’m a glider pilot, not a physicist, and my models and descriptions of how the Soaring Engine works are simplified to help you get a grip of the environment whilst you fly. Both wave and convergence systems are probably better described with more complex physics and a good deal of mathematics: you will not find this kind of analysis here. However I hope the simple sketches and quick explanations in this book will enable you to tackle even difficult and subtle soaring environments with success. Good luck!