Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines biodiversity loss. Polarized light pollution is a second type of that triggers water-seeking insects ovisposit on smooth dark man-made objects, because they simulate the polarization signatures natural water bodies. We document case study interaction these two forms conducting observations experiments near lamp-lit bridge over river Danube attracts mass swarms mayfly...

Multi-spectral imaging radiometry of the night sky provides essential information on light pollution (skyglow) and quality. However, due to different spectral sensitivity devices used for measurement, comparison surveys is not always trivial. In addition differences between measurement approaches, there a strong variation in natural radiance changes airglow. Thus, especially at dark locations, classical methods (such as Sky Quality Meters) fail provide consistent results. this paper, we show...

Using full-sky imaging polarimetry, we measured the celestial distribution of polarization during sunset and sunrise at partial (78% 72%) full (100%) moon in red (650 nm), green (550 blue (450 nm) parts spectrum. We investigated temporal change patterns degree p angle α linear sunlit moonlit skies dusk dawn. describe here position neutral points sky polarization, present video clips about transition twilight. found that a medium latitude (47° 15.481' N) this there is relatively short (10-20...

Aquatic insects detect water by the horizontal polarization of water-reflected light and thus are attracted to such light. Recently, in Hungarian Lake Balaton we observed dark patches forming between every autumn spring because inflow black suspended/dissolved organic matter into bright lake water. Earlier, characteristics surfaces were mapped imaging polarimeters from ground. In order measure reflection-polarization patterns these higher viewpoint flying polarotactic aquatic insects,...

Specific polarized light pollution (PLP) means the adverse influences of strongly and horizontally reflected from smooth dark artificial surfaces on polarotactic water-seeking aquatic insects. Typical PLP sources are photovoltaic panels. Using drone-based imaging polarimetry, in a solar panel farm, we measured reflection-polarization patterns fixed-tilt panels viewpoint flying insects, which most endangered targets potential victims such We found that temporal changes were complementary for...

Abstract Host-seeking female tabanid flies, that need mammalian blood for the development of their eggs, can be captured by classic canopy trap with an elevated shiny black sphere as a luring visual target. The design more efficient traps is important stock-breeders to control tabanids, since these blood-sucking insects cause severe problems livestock, especially horse- and cattle-keepers: reduced meat/milk production in cattle farms, horses cannot ridden, decreased quality hides due biting...

There are as many 18 theories for the possible functions of stripes zebras, one which is to cool animal. We performed field experiments and thermographic measurements investigate whether thermoregulation might work zebra-striped bodies. A zebra body was modelled by water-filled metal barrels covered with horse, cattle hides various black, white, grey striped patterns. The were installed in open air four months while their core temperature measured continuously. Using thermography,...

Numerous negative ecological effects of urban lighting have been identified during the last decades. In spite development technologies, detrimental effect this form light pollution has not declined. Several insect species are affected including night-swarming mayfly Ephoron virgo : when encountering bridges their mass swarming, these mayflies often fall victim to artificial lighting. We show a simple method for conservation exploiting positive phototaxis. With downstream-facing...

In recent decades, considerable research has been carried out both in measuring and modelling the brightness of sky. Modelling is highly complex, as properties light emission (spatial spectral distribution) are generally unknown, physical state atmosphere cannot be determined independently. The existing radiation transfer models lack focus on pollution model only a narrow range or do not consider realistic atmospheric circumstances. this paper, we introduce new Monte Carlo simulation for...

Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away Greenland, Newfoundland Baffin Island. Based an eleventh-century dial fragment artefact, found at Uunartoq in it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested sea proved to be efficient hand-held navigation tools, but dimensions incisions of find are from optimal this role. On basis sagas mentioning...

The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics which are similar to those water surfaces) attract water-leaving polarotactic insects. Thus, typical sources polarized light pollution endangering A new fashion fad is make car-bodies matt or grey. Since rough (matt) surfaces depolarize the reflected light, one ways reducing concerned surface. Consequently, black/grey may not induce pollution, would be an advantageous feature for...

If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, yellow Haidinger's brush can be perceived, long axis points towards sun. A band arcs across 90° person pick two on that band, observe brushes and triangulate position sun based orientation observed brushes. This method has been suggested to have used open sea by Viking navigators determine invisible occluded cloud or fog. Furthermore, also locate when...

It is a widely discussed hypothesis that Viking seafarers might have been able to locate the position of occluded sun by means dichroic or birefringent crystals, mysterious sunstones, with which they could analyze skylight polarization. Although atmospheric optical prerequisites and certain aspects efficiency this sky-polarimetric navigation investigated, accuracy main steps method has not quantitatively examined. To fill in gap, we present here results planetarium experiment measured...

The theory of sky-polarimetric Viking navigation has been widely accepted for decades without any information about the accuracy this method. Previously, we have measured first and second steps method in psychophysical laboratory planetarium experiments. Now, tested third step a experiment, assuming that are errorless. Using fists their outstretched arms, 10 test persons had to estimate elevation angles (measured numbers fingers) black dots (representing position occluded Sun) projected onto...

According to a famous hypothesis, Viking sailors could navigate along the latitude between Norway and Greenland by means of sky polarization in cloudy weather using sun compass sunstone crystals. Using data measured earlier atmospheric optical psychophysical experiments, here we determine success rate this sky-polarimetric navigation. Simulating 1000 voyages with varying cloudiness at summer solstice spring equinox, revealed chance which reach under conditions 3-week-long journey as function...

According to an old but still unproven theory, Viking navigators analysed the skylight polarization with dichroic cordierite or tourmaline, birefringent calcite sunstones in cloudy/foggy weather. Combining these their sun-dial, they could determine position of occluded sun, from which geographical northern direction be guessed. In psychophysical laboratory experiments, we studied accuracy first step this sky-polarimetric navigation. We measured adjustment error e rotatable cordierite,...

Abstract Multiple hypotheses have been proposed for possible functions of zebra stripes. The most thoroughly experimentally supported advantage stripes is their visual unattractiveness to horseflies (tabanids) and tsetse flies. We propose here a plausible hypothesis why biting avoid host animals with striped pelages: in sunshine the temperature gradients skin above slightly warmer blood vessels are difficult distinguish from induced by hairs at borderlines black cooler white To test this...

According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones determine the position of invisible Sun. After finding occluded Sun sunstones, its elevation angle had be measured shadow projected onto horizontal surface a sun compass. theory, these been birefringent calcite or dichroic cordierite tourmaline working as polarizers. It has frequently claimed that this...

The measurement of night sky quality has become an important task in conservation. Modern techniques involve mainly a calibrated digital camera or spectroradiometer. However, panchromatic devices are still prevalent to this day, even the absence determining spectral information sky. In case multispectral measurements, colour is currently presented multiple ways. One most frequently used metrics correlated temperature (CCT), which not without its limitation for purpose describing especially...