Observations, including from satellites, of the ash cloud from the Grímsvötn volcanic eruption.
Evidence of ash
Ash reports on Tuesday, 24 May, across northern Scotland confirmed Met Office ash forecasts issued on Monday.
Ash deposited on cars at Kirkwell airport, Orkney on 24 May
A helicopter flying over the north sea at 3pm on Tuesday encountered volcanic ash when flying between 2000 and 3000 ft, with ash being deposited on the aircraft.
A pilot reported to Teeside airport a layer of ash at 3200 ft approximately 100 miles off the Yorkshire coast.
Satellite and Lidar observations confirmed the presence of ash over northern Britain over the previous 24 hours.
A plane flying from Aberdeen to the Shetlands encountered volcanic ash during the flight with ash being deposited on the aircraft.
On Tuesday morning ash deposits were found on a plane that had been flying in the Orkney area.
A plane flying from Stansted to Belfast observed a layer of ash to the north /northwest of the flight path.
A plane flying at a height of 18,000 feet in the Manchester area around 2pm on Tuesday observed a layer of ash of approximately 1000-2000 feet thick.
The research ship Discovery entered an area of thick volcanic ash on Monday between Scotland and Iceland with ash being deposited onboard.
Professional observers reported ash being deposited in northern Britain.
Ash was deposited on vehicles on Orkney.
Air quality sensors across Scotland indicated an increased amount of ash particles (PM10s) during Tuesday.
Satellite image of ash cloud over UK on 24 May
Meteosat Second Generation (MSG)
MSG images are monitoring for the presence of volcanic ash emission in the vicinity of Iceland using infrared data from the Meteosat Second Generation (MSG) satellite. Because cloud particles and volcanic ash particles interact with the infrared radiation in different ways, data at several different wavelengths can be combined to identify the main ash plume, which, when present, would be shown as pink, yellow and orange colours in the images. However, it should be noted that it is only the thicker parts of the plume that are able to be detected by this method. In addition, the ash plume is often masked by overlying high cloud and therefore might not appear in the satellite image.
Polar orbiter imagery
Polar orbiter imagery can show the progression of the volcanic ash plume from the Grímsvötn volcano. This can be done using data from polar orbiting satellites operated by NOAA and EUMETSAT. As with the MSG images, these make use of the varying properties of the ash particles at different wavelengths. The ash cloud signal is pink, yellow and orange in this sequence.
Moderate Resolution Imagery
Generated by NASA/GSFC,
MODIS Rapid Response, these photo-like images provide useful information regarding the movement of dust and ash in the atmosphere. The dust shows up as a light brown/sandy colour.