Painted lady butterfly summer arrival

THIS April day is wild and beautiful, small white clouds high in a blue sky, and waves breaking in white horses on a blue sea.

The wind is from the east. It is bitter cold and, out on the headlands, blows with the force of a gale. As I round the promontory, it catches my trouser legs and fills them so that I am like a Michelin man from the waist down.

Beating into it, head down and leaning against the tempest, I see a raven pass 30 feet above me, drifting on stiff wings straight into the blast. Its forward motion amazes me. It is not being driven by the wind, but is sailing into it — and without a wing beat. Explain to me the aerodynamics of that!