Prince Albert sees "heat waves" in his side line of vision before his migraines.
What do they look like, do you know?
I have seen something best described as "bubbles" on occasion, a lot like the bubbles screensaver in Win7 only that the bubbles are larger, darker, and do not move like ordinary bubbles. They definitely look like bubbles, though.
On every occasion that's been it. No headaches afterwards, but typically the aura has lasted for around 40 minutes.