Dust and Haze

A hazy atmosphere can be often recognized when looking bottom down during a flight. Mostly the haze consists of aerosol particles, which have grown because of high humidity in the boundary layer and becloud the view. Predominantly this occurs in the morning and the evening, when the air slowly cools down and therefore relative humidity increases. Under these circumstances the top of the atmospheric boundary layer can be often noticed as more or less sharp "line". (See also Inversions and Status nasc., Smog BL Top.)

Haze1.jpg: A cloudless atmosphere at the end of the flight is shown here. One can recognize the different haze layers reaching from the boundary layer up to the cruising altitude. The Greek Islands can be dimly noticed at the bottom of the left side. So far I have only observed on this special flight that the whole troposphere from the ground to the tropopause was so hazy.

Haze2-5.jpg: This haze which is characteristic for the boundary layer came up at the descent to Sao Paolo in the late afternoon. The clouds were formed at the upper limit of the boundary layer.

Haze6-12.jpg: The haze, which could be observed during this flight, was predominantly caused by mineral dust particles. The air humidity was extremely low and the flight track ran above desert regions.

Haze13-20.jpg: Here the dusty haziness is most probably caused by air humidity. The aerosol particles swell up and hence increase their size. The cruising altitude was between 5000 and 6000 m. The inversion at the top from the boundary layer can be noticed as well as some clouds which are formed there. Taking the cruising altitude into account the boundary layer seems to be significantly above 2000 m - this is quite high.

Haze1.jpg: S. Borrmann, flight from Frankfurt to Heraklion (Crete), MINOS Field Campaign, 30 July 2001, 3:00 p.m. to 7:30 p.m.

Haze2-5.jpg: S. Borrmann, flight from Fortaleza to Sao Paulo, Brazil, 2 March 2004, 6:23 p.m. to 6:28 p.m. local time Sao Paulo

Haze6-12.jpg: S. Borrmann, Iran-Air flight from Teheran to Esfahan, 11 August 2005, 5:04 p.m. to 5:31 p.m.

Haze13-20.jpg: S. Borrmann, Cimber-Air flight QI1506 from Frankfurt to Kiel from 10:25 a.m. to 11:35 a.m.