Such pillars may appear as tall as 90 degrees depending on the height of the reflecting crystals and location of the observer. However, if viewed from a mountain top or aircraft, pillars formed by reflections from crystal upper surfaces can also be seen. From such vantage points, pillars extending below the light source are common. When the crystals are present near the near the surface such as during light falling snow, diamond dust and blowing snow, reflections may be seen from the upper surface of some crystals as well as the lower surface of others. This can produce pillars which extend both above and below the light source.
Street lighting can form such pillars.
Figure 7 shows how this happens. At times pillars occur simultaneously with other optical phenomena generated by ice crystals such as halos and sun dogs. However, blowing snow, ice fog and diamond dust can not only produce interesting pillars with sun or moon light, but also generate very interesting effects around strong artificial light sources. Spectrum Educational Enterprises . All Rights Reserved.