Simulation of inferior mirages observed at the Halligen Sea.

Two unusual forms of inferior mirage are observed and photographed at the Halligen Sea. With heuristic analytic functions for the temperature profiles, numerical integration of the refraction differ-ential equation on a flat earth is performed. The simulation shows that a double inferior mirage can appear if a light wind carries hot air from above dry sandbanks in the mud flats. Horizontal stripes can appear in the mirage image if a water channel crosses the line of sight between the observer and the object.

Simulation of inferior mirages observed at the halligen sea.

Two unusual forms of inferior mirage are observed and photographed at the Halligen Sea. With heuristic analytic functions for the temperature profiles, numerical integration of the refraction differential equation on a flat earth is performed. The simulation shows that a double inferior mirage can appear if a light wind carries hot air from above dry sandbanks in the mud flats. Horizontal stripes can appear in the mirage image if a water channel crosses the line of sight between the observer and the object.

Elliptical halos, Bottlinger's rings, and the ice-plate snow-star transition.

Elliptical halos and Bottlinger's rings are simulated by the use of a Monte Carlo algorithm that includes multiple scattering. High multiple reflections are required to obtain a sufficient brightness of the elliptical halos. By introducing three populations of nearly horizontal, gyrating, and swinging crystals, we obtain good agreement for four photographs of displays with ringlike and disklike structures. Through model experiments on the aerodynamical behavior of crystals, we find a new interpretation of the three populations. In this view elliptical halos and Bottlinger's rings occur in the transition region of ice plates with broad branches and stellar crystals at temperatures near -15 °C and large supersaturations. This interpretation is supported by a review of 23 reports of elliptical halo phenomena by members of the Finnish Halo Observers Network.

Simulation and analysis of pollen coronas.

By numerical simulation of light scattering by birch and pine pollen grains, we create color plates of coronas with vertical elliptical shapes and strong brightenings, respectively. The shape of the pollen is modeled by the union of n ellipsoids. The Fraunhofer integral is solved by the use of the fast Hartley transform. The sensitivity of the patterns to pollen orientation, Sun elevation, and pollen shape and size is discussed. Good agreement is obtained with amazing photographs made by a Finnish network of amateur astonomers, in the case of strong vertical orientation of the pollen axis.

Description of DIANA 2.

DIANA 2 is an improved version of a Fortran program DIANA for the analysis of electrophoresis and ultracentrifugation patterns by a sum of Gaussian-like distributions. This description may serve as manual for the use of the program DIANA 2.

A computer analysis of electrophoresis and ultracentrifugation patterns.

A program DIANA is designed to fit the scanning curves of electrophoresis and ultracentrifugation patterns with 10-15 overlapping peaks by a sum of Gaussian-like distribitions. The parameters of the distributions are adjusted by minimizing x, using a problem oriented minimizing procedure. The number of molecular components as well as starting values of the positions and the widths of the peaks must be choosen as input for each type of pattern. Programs are written in FORTRAN IV.