Landshut display, 25 Feb. 1996

This took place in variable cirrus cloud from around 11 - 13 hr local time (= UT + 1hr) with the Solar altitude ranging from 29 to nearly 33 degrees. With only a faint 22 degree halo, the remarkable features of this display were the bright parhelia, the upper tangental arc, the well-developed parhelic circle with 120 degree parhelia and faint but clearly visible Lowitz arcs. The clear bifurcation of the upper tangential arc appears to be due to the upper part of the Lowitz arc rather than to Parry's arc. There are few photographs of the rarely recorded upper and lower Lowitz arcs, thought to be produced by flat hexagonal plates spinning about a long axis. Landshut is NE of Munich on the river Isar and at 48deg 31min N; 12deg 10min E.

Photographs a - e taken on EC6009 transparency film with a Hassleblad and 80mm Planar lens, having a FOV 38deg (52deg diagonal), and a linear polarizer with E-vector directed radially to the Sun. The original scans have been unsharp masked to enhance the faint details. Photograph f is a portion of an image taken with a 35mm camera.

Click on the pictures for higher resolution (512 x 512) versions.

a, ~11:30 am

b, ~ 11:35 am

c, ~ 11:40 am

d, ~ 11:45 am - showing Lowitz arcs. A 1024 x 1024 version of the unprocessed original scan is shown

e, ~ 12:30 pm. Parhelic circle near 180 degrees

f, ~ 12:15 pm. Parhelic circle near 120 degrees (west).

Simulations computed with HALO. Halo 3 is a pre-release version (June 2000) - contact Les Cowley for details.

Photographs a, b, c, d overlayed on Halo 3 colour simulation

All sky simulation - zenith centred, 4.5 million rays, 256 grey levels, solar altitude: 32deg

Zoom simulation overlay of a - at correct scale, position and orientation. Alt=42; az=-21, FOV=38, solar altitude: 31.

Zoom simulation overlay of b - at correct scale, position and orientation. Alt=48; az=-2, FOV=38, 31.

Zoom simulation of d - centred at alt=40; az=-11, FOV=45, 5 million rays, 32 grey levels, solar altitude: 32

Landshut Lowitz + simulation of d - not exactly to same scale

Zoom simulation of d - at correct scale, position and orientation. Alt=42; az=-17, FOV=38, 6.7 million rays, 32 greys, solar altitude: 31.5. Overlay on photograph.

Setup parameters for HALO simulations

Composite of aligned photographs a-d and simulation. The images have been unsharp masked (75%, 30 pixels)

Animation of photograph d (unsharp masked) with a HaloSim3.5 simulation using column, plate, random and Lowitz crystals

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