As he passed over Redstone, British Columbia, Canada on an evening flight from Dallas, Texas to Anchorage, Alaska, US, Dan Chaney (Member 63,013) gazed out onto a grey panorama of Stratocumulus stratiformis, lined up in rows, called undulatus – with highlights picked out in coral pink by the light of the low Sun.

Or should that be lowlights, rather than highlights? When you zoom in close, some of the illuminated cloud tops appear to be below, rather than above, the grey cloudlets of the Stratocumulus.

One of the advantages of cloudspotting from the window seat is that the aircraft’s movement helps you distinguish the clouds’ relative altitudes. Due to the effect of parallax, those closer to your cruising altitude sweep across your view faster than those further below. Based on this, Dan determined that the pink parts were in fact the tops of Cumulus that were below the majority of the grey Stratocumulus layer. The light was just catching them as it shone between the levels. Such an effect would normally last just a few minutes, but the direction of Dan’s flight prolonged the colourful display as they chased the Sun westward over Canada.