Small air bubbles on the rear inside surface of a water-filled cylinder, near its edges, appear horizontally elongated, joined in pairs, and take on color. Similarly, if an extended object is sufficiently close to the water-filled cylinder, three images of the object are seen when looking through the cylinder. The center image joins onto the left or right image as the observer moves his or her head back and forth in front of the cylinder. The first observation is explained in terms of glare points of light, and the real and virtual parts of the external caustic of the light transmitted through the water-filled cylinder. The second observation is explained as an example of Berry's caustic touching theorem which describes the topological method of fragmentation of an object's image into multiple images. For the situation studied here, an imaginary cylindrical aberration caustic of the water-filled cylinder decomposes object space into a three-ray region sandwiched between two one-ray regions. As an extended object crosses the caustic boundary from one of the one-ray regions into the three-ray region, an image-pair creation event occurs, which is followed by an image-pair disconnection event producing the three images. Similarly, when the extended object crosses the caustic boundary from the three-ray region into one of the one-ray regions, an image-pair merging event occurs, which is followed by an image-pair annihilation event producing the one remaining image.All-sky polarization images were measured from sunrise to sunset and during a cloud-free totality on 21 August 2017 in Rexburg, Idaho using two digital three-camera all-sky polarimeters and a time-sequential liquid-crystal-based all-sky polarimeter. Twenty-five polarimetric images were recorded during totality, revealing a highly dynamic evolution of the distribution of skylight polarization, with the degree of linear polarization becoming nearly zenith-symmetric by the end of totality. The surrounding environment was characterized with an infrared cloud imager that confirmed the complete absence of clouds during totality, an AERONET solar radiometer that measured aerosol properties, a portable weather station, and a hand-held spectrometer with satellite images that measured surface reflectance at and near the observation site. These observations confirm that previously observed totality patterns are general and not unique to those specific eclipses. The high temporal image resolution revealed a transition of a neutral point from the zenith in totality to the normal Babinet point just above the Sun after third contact, providing the first indication that the transition between totality and normal daytime polarization patterns occurs over of a time period of approximately 13 s.A water drop hanging from a house siding board after a rain shower is near-normally illuminated by sunlight either shortly after sunrise or before sunset. A focusing caustic consisting of a bright V-shape or U-shape with a small bright elliptical shape immediately above it is frequently seen on the next lower siding board. In addition, there are two broad regions of illumination immediately above the caustic, fanning out to the upper left and upper right. This complicated pattern, composed of a bright V-shape or U-shape, and the bottom half of the small bright elliptical-shape immediately above it, is caused by the hyperbolic umbilic diffraction caustic near the condition of maximum focus. This can be observed because, by a stroke of good fortune, the distance between the lower edge of a siding board and the flat portion of the next siding board beneath it is nearly equal to the paraxial focal distance of the caustic. Blocking off the light incident on the top, bottom, left side, and right side of the drop was used to determine the portion of the drop responsible for different parts of the caustic. The results were found to match the predictions for the hyperbolic umbilic caustic.For an accurate modeling of natural rainbows, it is necessary to take into account the flattened shape of falling raindrops. Larger drops do also oscillate, and their axes exhibit tilt angles with respect to the vertical. In this paper, I will discuss two rare rainbow phenomena that are influenced by these effects bright spots belonging to various rainbow orders, but appearing at remarkable angular distances from their traditional locations, as well as triple-split primary rainbows. While the former have not been observed in nature so far, the latter have been documented in a few photographs. This paper presents simulations based on natural drop size distributions using both a geometric optical model, as well as numerically calculated Möbius shifts applied to Debye series data.Visual ranges of up to 440 km have recently been documented by photographs of ground-based observers. A report from 1948 claimed a record visual range from a plane of more than 530 km and a similar recent observation from 2017 was documented by a photo. Such extreme visual ranges can in principle be explained by the interplay of refraction and light scattering. However, they require optimal atmospheric conditions, and cleverly chosen locations and times.A photographic observation sequence was obtained of a subsun before, during, and after the total phase of the 2016 solar eclipse. The time-resolved images were obtained from a high-altitude jet aircraft. The image sequence was searched for the possible presence of a solar corona-generated subsun during totality. Although the subsun-creating conditions apparently persisted during totality, the drop in signal intensity compared to the local background prevented its detection.  https://www.selleckchem.com/products/atglistatin.html  Separately, we document a visual observation from the 1977 total solar eclipse of a rainbow that faded, in the last a few seconds before totality, from being normally multicolored to monochromatic red from water drops then predominantly illuminated by light from the solar chromosphere. A similar transition in the final seconds before, and after, totality is expected to occur for parhelia. The posited short-living monochromatic red parhelion resulting from the momentary illumination of ice crystals by the solar chromosphere is still waiting to be observed.