Into the blue: thermaling & flying XC on blue days

November 16, 2020

Blue day is a shortening of the term "blue thermal day" which is the origin of the phrase according to some gliding sources. This means that the "blue" description refers purely to the lack of cumulus clouds in the layer we get thermal activity in, not the whole sky. Simpler approaches look at the sky as a whole. So how do we make the most of these 'blue days' when we’re trying to fly cross country? Here’s some background and some tips, hopefully it helps you understand what’s going on and provide some tools to use when you next find yourself out on a blue day.