By Dr Claire Ryder, Department of Meteorology, University of Reading
Some of the headlines about Monday’s orange sky
Monday’s red sun and the yellowy-orange sky produced an eerie atmosphere, and some beautiful photos, but what was the cause?
We’re used to seeing red skies at sunset, or even at dawn if we’re up early enough, but a red sun throughout the day is an extremely unusual event over the UK. A few unusual events combined this week to give us a blood-red sun for much of the day.
Firstly, we were under the effect of southerly air flow, associated with ex-hurricane Ophelia. While the centre of the storm was out to the west, central and southern England had relatively cloud-free skies allowing the sun to be seen.
Secondly, this southerly airflow brought both Saharan dust, whipped up by strong winds over desert surfaces, and smoke particles from wildfires over Portugal and Spain, lofted to high altitudes and transported our way. The combination of these two types of particles in the atmosphere then led to the red sun and orange skies.