Tuesday, July 21, 2009

Volcanic Twilights

On June 12, 2009, one of the most active volcanoes of the Kuril islands near Kamtschatka, which is situated near the northwestern end of the island of Matua, Sarychev Peak, erupted.

A NASA picture taken from the ISS gives an impressive sight of the eruption. Ashes have been ejected up to 20 kms into the atmosphere. Only a few hours after the eruption, the sulfur dioxide cloud of the volcano covered an area of 2.407 kms in width and 926 kms in length above the island. During the following weeks, the aerosoles spread over the whole northern hemisphere.

Since the end of June, also in Central Europe unusual twilights are observed. The up-to-date Lidar measurement from the Hohenpeissenberg observatory in Bavaria shows three aerosol layers in altitudes of 15, 18 and 22 kms in comparison to the eruption of Mt. Pinatubo. It is very interesting that the layers in 15 and 18 kms have come here with westerly winds passing over Alaska, Canada and the Atlantic Ocean, while the layer in 22 kms has been transported to us by stratospheric easterly winds passing over Asia (Russia/China). So the volcanic aerosoles have travelled around half of the planet in two different directions (the lower layers eastward and the upper one westward), meeting again here over Europe. I think this is worth to be mentioned.

On July 4, Peter Krämer observed the caracteristic crepuscular rays (picture above). On July 13, Reinhard Nitze photographed the most spectacular volcanic twilight in Barsinghausen near Hanover (Fig. 3
). In his picture, the high aerosol clouds can easily be recognized. These clouds still receive sunlight while normal cirrus clouds are already within the shadow of the earth.

During the past few days, there were also noctilucent clouds visible, which passed over to the reddish aerosol clouds in lower layers. There should be unusual twilights visible also during the following weeks.

Saturday, July 04, 2009


July 11, 2008:

I was very astonished when I was working and suddenly a horsefly fell upon my workbench.
The animal was about 3.5 cms in length. It was a very hot day, and the “flying fellow” had obviously lost his way, landed up in the workshop and could not find the way out. Well, the animal was lying there without moving, and the sunlight caused nice diffraction colours in its big compound eyes.

Author: Michael Großmann, Kämpfelbach, Germany


On May 13, 2008, I was flying to Tunisia. Just before the plane landed in Monastir, I looked out of the window and saw a faint onset of a red rainbow. About one minute later, the rain became heavier, and the bow became more intensive, even below the horizon. Unfortunately, the plane landed about two minutes later, and I could not see if the red rainbow was visible from the ground.

Author: Michael Großmann, Kämpfelbach, Germany


March 10, 2009:

There is not always fine weather outside for making pretty pictures. So I tried to take some photographs of backlighted hot water vapour. Surprisingly, some pretty irisation colours appeared, which kept constantly changing in the rising “fountains”. Even after a short time, as the water cools down, the colours become less intensive as they are when the water is very hot.

Author: Michael Großmann
, Kämpfelbach, Germany