Physicists track atmospheric particles producing Monday's red sky

October 18, 2017, University of Hertfordshire
Physicists track atmospheric particles producing Monday’s red sky
Sky and sun over University of Hertfordshire Observatory at Bayfordbury on 17 October 2017. Credit: David Campbell and the University of Hertfordshire

Atmospheric physicists from the University of Hertfordshire have been tracking the atmospheric particles responsible for the stunning red sky and sun seen across parts of south-east England on Monday afternoon.

Using a Lidar, a laser ranging instrument, at the University's Bayfordbury Observatory near Hertford, the team monitored the height of the throughout the day. Laser pulses reflected from the particles show their arrival around midday, their growing height in the atmosphere, and their eventual departure in the evening.

The atmospheric profile was measured every second, allowing the changes in the particle layering to be observed throughout the day. The particles responsible for the red sky are seen as a diagonal stripe in the profile sequence. The layer of dust arrived over Hertford around 11:00 GMT at 1 km altitude, drifted past over the next 6 hours at progressively higher altitudes, and reached 2-3 km altitude by the time it moved away from Hertford around 18:00 UTC.

During the time the particles sat over England, the sky acquired a reddish hue and the sun appeared distinctly red, due to the preferential scattering of blue light by the particles (main image).

Professor Joseph Ulanowski of the University computed the likely path taken by the particles over the preceding six days, prior to their arrival over England, using the NOAA HYSPLIT trajectory model. These computations show that the air passed over both the Saharan desert and Portugal, picking up desert dust from the Algeria-Mauritania region of the Sahara and potentially also bushfire smoke from Portugal, which the air then carried over south-east England.

Dr Matthias Tesche, a meteorologist at the University of Hertfordshire, noted the role of tropical storm Ophelia in producing Monday's rare views of the sun and sky. "The presence of Ophelia in the region greatly affected the larger-scale circulation patterns and enabled it to tap into the reservoir of Saharan dust and lead it straight to the UK and Ireland," he said.

Atmospheric physicists at the University of Hertfordshire regularly monitor and pollutants as part of their research into air quality, climate change and light scattering.

Explore further: Tropical Storm Ophelia appears as a comma in NASA imagery

Related Stories

Tropical Storm Ophelia appears as a comma in NASA imagery

October 11, 2017

Infrared imagery from NASA's Aqua satellite showed powerful thunderstorms around the center of Tropical Storm Ophelia with a band of thunderstorms stretching to the southwest, giving the storm the appearance of a comma.

Storm brings 'apocalyptic' skies to Britain

October 16, 2017

The sun shone red and the sky darkened to a foreboding orange and brown across parts of Britain on Monday, as a storm swept air and dust in from southern Europe.

Unexpected discovery could impact on future climate models

February 10, 2009

( -- Astronomers have made an unexpected find using a polarimeter (an instrument used to measure the wave properties of light) funded by the Science and Technology Facilities Council (STFC), that has the potential ...

New instrument for NASA unmanned aircraft

March 11, 2015

Scientists at the University of Hertfordshire have designed and built a new type of instrument for climate research that is capable of detecting and analysing microscopic airborne particles at altitudes twice as high as a ...

Recommended for you

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

OSIRIS-REx reveals asteroid Bennu has big surprises

March 19, 2019

A NASA spacecraft that will return a sample of a near-Earth asteroid named Bennu to Earth in 2023 made the first-ever close-up observations of particle plumes erupting from an asteroid's surface. Bennu also revealed itself ...

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...

Revealing the rules behind virus scaffold construction

March 19, 2019

A team of researchers including Northwestern Engineering faculty has expanded the understanding of how virus shells self-assemble, an important step toward developing techniques that use viruses as vehicles to deliver targeted ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.