TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Manche mögen‘s kochend heiß JF - Physik in unserer Zeit Y1 - 2019 U6 - https://doi.org/10.1002/piuz.201901533 VL - 50 IS - 1 SP - 46 EP - 47 PB - Wiley-VCH ER - TY - BOOK A1 - Vollmer, Michael T1 - Atmosphärische Optik für Einsteiger, Lichtspiele in der Luft Y1 - 2019 SN - 978-3-662-58362-3 U6 - https://doi.org/10.1007/978-3-662-58362-3 PB - Springer Spektrum CY - Berlin / Heidelberg ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Die Qual der Wahl an Weihnachten JF - Physik in unserer Zeit Y1 - 2018 U6 - https://doi.org/10.1002/piuz.201801528 VL - 49 IS - 6 SP - 306 EP - 306 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Infrared cameras as accessories to smartphones: facts you need to know JF - Physics Education Y1 - 2018 U6 - https://doi.org/10.1088/1361-6552/aae277 VL - 53 IS - 6 SP - 065019 EP - 065019 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Und sie dreht sich doch … JF - Physik in unserer Zeit Y1 - 2018 U6 - https://doi.org/10.1002/piuz.201801525 VL - 49 IS - 5 SP - 254 EP - 254 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Slow Speed – Fast Motion. Funktion und Technik von Zeitrafferkameras JF - Physik in unserer Zeit Y1 - 2018 U6 - https://doi.org/10.1002/piuz.201801507 VL - 49 IS - 4 SP - 190 EP - 193 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Von Eiswürfeln und gefrorenen Seen JF - Physik in unserer Zeit Y1 - 2018 U6 - https://doi.org/10.1002/piuz.201801518 VL - 49 IS - 4 SP - 201 EP - 202 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Direct speed of sound measurement within the atmosphere during a national holiday in New Zealand JF - Physics Education Y1 - 2018 U6 - https://doi.org/10.1088/1361-6552/aab6ce VL - 53 IS - 3 SP - 033007 EP - 033007 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Time-lapse videos for physics education: specific examples JF - Physics Education Y1 - 2018 U6 - https://doi.org/10.1088/1361-6552/aab6cf VL - 53 IS - 3 SP - 033007 EP - 033007 ER - TY - JOUR A1 - Vollmer, Michael A1 - Shaw, Joseph A. A1 - Nugent, Paul A1 - Harris, Wilson T1 - Heiße Quellen im Wärmebild. Yellowstone‐Park im Infraroten JF - Physik in unserer Zeit Y1 - 2019 U6 - https://doi.org/10.1002/piuz.201901539 VL - 50 IS - 5 SP - 244 EP - 250 PB - Wiley-VCH ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Alles kalter Kaffee? Rasante Physik JF - Physik in unserer Zeit Y1 - 2019 U6 - https://doi.org/10.1002/piuz.201901553 VL - 50 IS - 5 SP - 252 EP - 253 PB - Wiley-VCH ER - TY - CHAP A1 - Vollmer, Michael A1 - Shaw, Joseph A. T1 - Near infrared photography of atmospheric optical phenomena T2 - Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019 T3 - Proceedings of SPIE - Vol. 11143 Y1 - 2019 U6 - https://doi.org/10.1117/12.2523165 SP - 111431P-1 EP - 111431P-6 CY - Quebec City, Quebec, Canada ER - TY - CHAP A1 - Vollmer, Michael A1 - Shaw, Joseph A. T1 - Extended visual range: an observation during a total solar eclipse T2 - Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019 T3 - Proceedings of SPIE - 11143 Y1 - 2019 U6 - https://doi.org/10.1117/12.2523167 SP - 111431Q-1 EP - 111431Q-6 CY - Quebec City, Quebec, Canada ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Slow speed—fast motion: time-lapse recordings in physics education JF - Physics Education Y1 - 2018 U6 - https://doi.org/10.1088/1361-6552/aaa954 VL - 53 IS - 3 SP - 035019 EP - 035019 ER - TY - JOUR A1 - Möllmann, Klaus-Peter A1 - Regehly, Martin A1 - Vollmer, Michael T1 - Spectroscopy and microscopy analysis of semiconductor lasers in student laboratories JF - European Journal of Physics Y1 - 2020 U6 - https://doi.org/10.1088/1361-6404/ab5075 VL - 41 IS - 2 SP - 025302 PB - Institute of Physics Publishing (IOP); European Physical Society ER - TY - JOUR A1 - Vollmer, Michael A1 - Shaw, Joseph A. T1 - Extended visual range during solar eclipses JF - Applied Optics Y1 - 2018 U6 - https://doi.org/10.1364/AO.57.003250 VL - 57 IS - 12 SP - 3250 EP - 3259 ER - TY - JOUR A1 - Vollmer, Michael T1 - Asymmetrische Polarlichter JF - Physik in unserer Zeit Y1 - 2009 U6 - https://doi.org/10.1002/piuz.200990107 VL - 40 IS - 6 SP - 275 EP - 275 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Unsichtbares sichtbar gemacht: Infrarotkameras für Smartphones JF - Physik in unserer Zeit KW - Infrarotkamera KW - Smartphone KW - Temperaturmessung KW - räumliche Auflösung KW - qualitative Analyse KW - quantitative Analyse Y1 - 2020 U6 - https://doi.org/https://doi.org/10.1002/piuz.201901551 VL - 51 IS - 1 SP - 29 EP - 35 PB - Wiley-VCH ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Wenn Licht die Biege macht JF - Physik in unserer Zeit Y1 - 2020 U6 - https://doi.org/https://doi.org/10.1002/piuz.202001569 VL - 51 IS - 1 SP - 46 EP - 47 PB - Wiley-VCH ER - TY - JOUR A1 - Vollmer, Michael T1 - Gefrierende Gewässer JF - Physik in unserer Zeit KW - Gefrieren von Seen KW - Eiswachstumsmodell KW - Konvektion KW - Strahlung KW - Stefan-Boltzmann-Gesetz KW - Wärmeleitfähigkeit KW - optische Eisdickenmessung Y1 - 2021 U6 - https://doi.org/10.1002/piuz.202001589 VL - 52 IS - 1 SP - 19 EP - 25 PB - Wiley-Blackwell ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Fata Morgana im Wasserbecken JF - Physik in unserer Zeit KW - Fata Morgana KW - Luftspiegelung Y1 - 2020 U6 - https://doi.org/10.1002/piuz.202001575 VL - 51 IS - 2 SP - 98 EP - 99 PB - Wiley-Blackwell ER - TY - CHAP A1 - Richards, A. A1 - Hübner, M. A1 - Vollmer, Michael ED - Holst, Gerald C. T1 - Measurements of SWIR backgrounds using the swux unit of measure T2 - Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIX : 17-18 April 2018, Orlando, Florida, United States T3 - Proceedings of SPIE - 10625 KW - Short wave infrared radiation KW - Sensors KW - Light sources and illumination KW - Cameras KW - Sun KW - Calibration Y1 - 2018 U6 - https://doi.org/10.1117/12.2305282 PB - SPIE CY - Bellingham, Washington, USA ER - TY - JOUR A1 - Vollmer, Michael A1 - Mustard, Alexander T1 - Blue - the color of (pure) water JF - Physics Education N2 - Water can exhibit many different colors due to a variety of physical properties. Here, we focus on some observable colors within very pure freshwater. We only treat the absorption of light due to electronic and ro-vibrational excitations and scattering due to refractive index fluctuations of the water and the respective consequences for the appearance of colors. Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/1361-6552/ab130a U6 - https://doi.org/10.1088/1361-6552/ab130a SN - 0031-9120 (print) 1361-6552 (online) IS - Ausgabe: 4/ Band: 54 PB - IOP Publishing ER - TY - JOUR A1 - Vollmer, Michael T1 - The freezing of lakes in winter JF - European Journal of Physics N2 - Freezing of lakes is described using a simplified one-dimensional model, which gives ice thickness, ice growth rates, and ice surface temperature as a function of time. Model data for a specific lake with known meteorological conditions are compared to estimated ice thickness using a simple optical method. Finally, more advanced potential students projects are briefly discussed and results of a numerical solution are compared to the simplified model. Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/1361-6404/ab07f8 U6 - https://doi.org/10.1088/1361-6404/ab07f8 SN - 1367-2630 IS - Ausgabe: 3/ Band: 40 PB - IOP Publishing ER - TY - JOUR A1 - Vollmer, Michael T1 - Die Grenzen des Auges JF - Physik Journal N2 - Mithilfe geeigneter Hilfsmittel lassen sich die Wahrnehmungsgrenzen des Auges überwinden. Menschliche Augen weisen räumliche, zeitliche und spektrale Begrenzungen auf, welche die Wahrnehmung einschränken. Geeignete optische Geräte und Kameras helfen, diese zu überwinden und eine große Vielfalt an physikalischen Phänomenen für die Lehre zu erschließen. Die Angaben zu den Anteilen an aufgenommener Information durch die menschlichen Sinnesorgane schwanken meist zwischen etwa 81 und 87 Prozent für die Augen, 10 bis 11 Prozent für die Ohren und dem Rest für schmecken, riechen und tasten. Das Produktmarketing macht sich dies gezielt zunutze. Offensichtlich ist für alle subjektiven Wahrnehmungen unserer Umwelt das Auge sehr wichtig; in Bezug auf räumliche und zeitliche Auflösung sowie spektrale Empfindlichkeit ist es jedoch eingeschränkt. Die dadurch entstehenden Wahrnehmungsgrenzen für physikalische Vorgänge und Objekte lassen sich durch geeignete optische Geräte mit – das Auge ersetzenden – Sensoren in Kamerasystemen überwinden (Abb. 1). Dies erhöht die Zahl beobachtbarer technischer und natürlicher Phänomene und den daraus gewonnenen Informationsgehalt deutlich. Da entsprechende Kameras relativ preiswert sind und sich damit viele einfache Experimente erfolgreich demonstrieren lassen, kann ein gezielter Einsatz die Lehre der Physik an Schulen und in einführenden Vorlesungen an Hochschulen bereichern und den Einstieg in verwandte Gebiete wie die Infrarotastronomie vorbereiten. (...) Y1 - 2023 IS - 3 SP - 28 EP - 33 ER - TY - JOUR A1 - Vollmer, Michael T1 - The evolution of IR imaging: What’s next? JF - Laser Focus World Magazine N2 - The vast majority of all human sensory inputs occur through our eyes. Light from direct sources or scattered light from objects enters our eyes and is focused onto the retina. The resulting signals are interpreted by the brain, which leads to the perception of the image of the observed objects. Although quite efficient for our daily life, many technological applications require sensor properties beyond the characteristics of our eyes. A major limitation regarding microscopic objects is spatial resolution, which is overcome by microscopes. Time resolution can be dealt with using either time-lapse or high-speed cameras. Finally, eyes only detect visible radiation within the wavelength range from about 380 nm to 780 nm. Changing the detected spectral range of electromagnetic radiation can dramatically enhance our vision. Shorter wavelengths such as x-rays are valuable tools for medical imaging, while ultraviolet (UV) imaging is used for forensics. Longer-wavelength thermal radiation used for imaging is often defined within spectral ranges, characterized by the photoelectric detector materials used and the respective atmospheric windows. Y1 - 2022 UR - https://www.laserfocusworld.com/detectors-imaging/article/14233175/the-evolution-of-ir-imaging-whats-next SP - 23 EP - 26 PB - endeavor business media ER - TY - CHAP A1 - Vollmer, Michael ED - Haglund, Jesper ED - Jeppsson, Fredrik ED - Schönborn, Konrad J. T1 - Fundamentals of Thermal Imaging T2 - Thermal Cameras in Science Education N2 - The quantitative explanation of thermal radiation in 1900 by Max Planck started a development, which today has resulted in modern infrared technologies with thermal imaging cameras. The present work briefly describes the fundamentals of infrared imaging, based on the fact, that every object at a temperature T > 0 K emits thermal radiation. Its amount is only governed by temperature and the material quantity emissivity. Factors that define types and properties of commercial IR cameras, such as temperature range in nature and industry, the atmospheric windows for IR radiation as well as available optics and detectors are discussed. A short summary of typical specifications of IR cameras and interpretation of recorded images is given. Y1 - 2022 U6 - https://doi.org/10.1007/978-3-030-85288-7_2 SP - 7 EP - 25 PB - Springer CY - Cham ER - TY - CHAP A1 - Vollmer, Michael ED - Haglund, Jesper ED - Jeppsson, Fredrik ED - Schönborn, Konrad J. T1 - Infrared Cameras as Smartphone Accessory: Qualitative Visualization or Quantitative Measurement? T2 - Thermal Cameras in Science Education N2 - Recently, infrared cameras have become available as smartphone accessories. Being less expensive than regular infrared cameras they are readily affordable and widespread use in the future is expected. Available commercial models are compared and examples for meaningful use and interpretation of respective qualitative images is given. The respective arguments also directly apply to other commonly used low-grade IR cameras with similar pixel resolution and frame rates. It is assumed that users know about the typical problems due to, e.g., thermal reflections. Rather than discussing those, focus is on the danger of wrong interpretations, in particular with regard to the low frame rate, the often implemented image processing within the cameras, the imposed restrictions on necessary input parameters, and the extremely limited spatial resolution and respective errors in potential quantitative analyses. Y1 - 2022 U6 - https://doi.org/10.1007/978-3-030-85288-7_9 SP - 129 EP - 145 PB - Springer CY - Cham ER - TY - CHAP A1 - Vollmer, Michael ED - Gómez-López, Vicente M. ED - Bhat, Rajeev T1 - Physics of the Electromagnetic Spectrum T2 - Electromagnetic Technologies in Food Science N2 - Electromagnetic (EM) waves, spanning about 15 orders of magnitude of wavelength (or frequency or energy) from radio waves via microwaves, infrared radiation, visible light, ultraviolet radiation, and X-rays to the highly energetic γ-rays, are utilized in food processing. In order to explain all uses of these waves in the food industry, the chapter begins with a general discussion of properties of waves and their description with wavelength frequency, speed of propagation, and also energy transport. Using visible light as starting point, electromagnetic waves in other wavelength regimes are discussed. The interaction of EM radiation with matter reveals that the wave description alone is insufficient to explain all observed phenomena. Understanding the attenuation of EM radiation in matter requires knowledge of the particle properties of electromagnetic waves, most easily summarized by the concept of photons which carry energy as well as momentum. This wave–particle duality does apply not only to EM waves, i.e. photons, but also to the particles which build up matter, in particular electrons, which also need to be described as waves. This leads to respective quantum mechanical explanations of the microscopic structure of matter in the form of atoms, molecules, and nuclei. Knowledge of their structure is a prerequisite to understand, first, the generation of EM radiation and, second, also its interaction with matter. As a result, it will become obvious that there are mostly three different usages of EM radiation in the food industry: preserving, characterizing, and heating. Y1 - 2022 U6 - https://doi.org/10.1002/9781119759522.ch1 SP - 1 EP - 32 PB - Wiley CY - Chichester, UK ER - TY - JOUR A1 - Vollmer, Michael T1 - So weit das Auge trägt JF - Physik in unserer Zeit N2 - Sichtweiten in der Atmosphäre reichen von wenigen Metern im Nebel bis zu einigen hundert Kilometern bei extrem guten Fernsichtbedingungen. Die zugrundeliegende Physik geht vom Wahrnehmungskontrast aus. Dieser ändert sich mit der Entfernung entlang der Sichtlinie zwischen Objekt und Auge aufgrund von Lichtstreuung und Absorption an den Bestandteilen der Atmosphäre. Dazu kommt bei der Fernsicht die Refraktion, die es erlaubt, auch über den durch die Kugelform der Erde geometrisch bedingten Horizont hinaus zu sehen. Y1 - 2023 UR - https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/piuz.202301675 U6 - https://doi.org/10.1002/piuz.202301675 SN - 1521-3943 VL - 54 IS - 5 SP - 222 EP - 230 PB - Wiley ER - TY - JOUR A1 - Vollmer, Michael A1 - Eberhardt, Wolfgang T1 - Ein einfaches Modell für die Vorhersage von CO2 Konzentrationen in der Atmosphäre in Abhängigkeit von globalen CO2 Emissionen JF - PhyDid B, Didaktik der Physik, Beiträge zur DPG-Frühjahrstagung N2 - Es wird das vielleicht einfachst mögliche Modell vorgestellt, mit dem zeitabhängige CO2 Konzent-rationen c(t) in der Atmosphäre ausgehend von verschiedenen globalen Emissionsszenarien für CO2berechnet werden. Dazu wird eine einzelne inhomogene lineare Differenzialgleichung 1. Ordnung hergeleitet, deren Parameter sich aus den quantitativen Daten des global carbon project sowie Mauna Loa Daten für CO2 Konzentrationen errechnen. Das Modell wird erstens getestet am Zeitraum 1960 bis 2020 mit vergleichsweise guter quantitativer Übereinstimmung zu Messdaten. Zweitens wird für zwei typische IPCC Emissions-Szenarien ein Vergleich der Modellvorhersagen mit denen der kom-plexen IPCC Earth-System-Klimamodelle diskutiert mit qualitativer Übereinstimmung des zeitli-chen Verlaufs. Drittens werden Ergebnisse einiger ausgewählter neuer Emissionsszenarien präsen-tiert. Ungeachtet einiger Abweichungen zu komplexeren Klimamodellen zeichnet sich unser Mo-dell durch zwei wichtige Vorteile für die Lehre aus. Zum einen ist es sehr einfach für Studierende und begabte Schüler nutzbar, da die erforderliche Lösung der Differentialgleichung bereits mit han-delsüblicher Tabellenkalkulationssoftware wie z.B. Excel programmiert werden kann. Dadurch ge-stattet es zum anderen auch sehr einfach, den zeitlichen Verlauf von Emissionsszenarien zu verän-dern und innerhalb weniger Sekunden Veränderungen aufgrund geänderter Eingaben zu berechnen. Insofern eignet sich das Modell sehr gut als Einstieg in das Thema Klimamodellierung in einführen-den Hochschulvorlesungen zum Themenbereich Kohlenstoffkreislauf und Klimawandel. In der Schule kann es gegen Ende der Sekundarstufe 2 beispielsweise im Projektunterricht zum Themen-komplex Nachhaltigkeit in Physik und/oder Mathematik eingesetzt werden Y1 - 2024 UR - https://ojs.dpg-physik.de/index.php/phydid-b/article/view/1411 SN - 2191-379X VL - 1 IS - 1 SP - 379 EP - 388 PB - FU Berlin ER - TY - JOUR A1 - Vollmer, Michael A1 - Eberhardt, Wolfgang T1 - A simple model for the prediction of CO2 concentrations in the atmosphere, depending on global CO2 emissions JF - European Journal of Physics N2 - We present a very simple model for estimating time dependent atmospheric CO2 concentrations c(t) from global carbon emission scenarios, serving as single input data. We derive a single linear differential equation of 1st order, based on parameters which are estimated from quantitative data of the global carbon project and Mauna Loa data for CO2 concentrations. The model is tested first by comparing it to the 1960–2021 period with reasonably good quantitative agreement and, second to two of the typical current IPCC scenarios with good qualitative agreement. Finally, some new emission scenarios are modelled. Despite several drawbacks concerning absolute quantitative predictions, there are two important advantages of the model. First, it can be easily executed by students already with simple programmable spreadsheet programs such as Excel. Second input emission scenarios can be changed easily and expected changes are immediately seen for discussion during undergraduate and graduate courses on the carbon cycle and climate change. Y1 - 2024 U6 - https://doi.org/10.1088/1361-6404/ad230d VL - 45 IS - 2 ER - TY - JOUR A1 - Vollmer, Michael T1 - Limitations of the eye and how to overcome them JF - Journal of Physics: Conference Series N2 - Human eyes have spatial, temporal, and spectral limitations which impose constraints on our perception. With appropriate optical devices and cameras, the limitations can be easily overcome. As a consequence, a huge variety of physical phenomena can be made accessible for teaching. Y1 - 2024 U6 - https://doi.org/10.1088/1742-6596/2750/1/012001 VL - 2750 IS - 1 SP - 1 EP - 10 ER - TY - JOUR A1 - Vollmer, Michael T1 - Nachtsicht ins All mit dem bloßen Auge: Sag mir, wie weit die Sterne steh'n JF - Physik in unserer Zeit Y1 - 2025 U6 - https://doi.org/10.1002/piuz.202501751 VL - 2025 SP - 2 EP - 10 PB - Wiley ER - TY - JOUR A1 - Vollmer, Michael T1 - Naked eye celestial objects and phenomena: how far can we see at night? JF - European Journal of Physics N2 - How far can we see with the naked eye at night? Many celestial objects like stars and galaxies as well as transient phenomena such as comets and supernovae can be observed in the night sky. We discuss the furthest distances of such objects and phenomena observable with the naked eye during the night-time for Earth-bound observers. The physics of night-time visual ranges differs from that of daytime observations because human vision shifts from cones to rods. In addition, mostly point sources are observed due to the large distances involved. Whether celestial objects and phenomena can be detected depends on the contrast of their radiation and the background sky luminance. We present a concise overview of how far we can see at night by first discussing the effects of the Earth's atmosphere. This includes attenuation of transmitted radiation as well as its role as a source of background radiation. Disregarding the attenuation of light due to interstellar and intergalactic dust, simple maximum night-time visual range estimates are based on the inverse square law, which can be easily verified by laboratory and demonstration experiments. From the respective calculations, we find that individual stars within the Milky Way galaxy of up to 15 000 light years are observable. Even further away are observable galaxies with several billion stars. The Andromeda galaxy can be observed with the naked eye at a distance of around 2.5 million light years. Similarly, the observability of supernovae also allows a visual range beyond the Milky Way galaxy. Finally, gamma ray bursts as the most energetic events in the universe are discussed concerning naked eye observations. Y1 - 2025 U6 - https://doi.org/10.1088/1361-6404/adbf74 VL - 46 IS - 3 PB - IOP Science ER - TY - JOUR A1 - Vollmer, Michael T1 - How far can we see at day? JF - European Journal of Physics N2 - We discuss the farthest objects on Earth observable for the unaided, healthy naked eye during the daytime, i.e., the maximum visual range for observers on Earth. Visual range depends first on the properties of the material between observer and object and its interaction processes with radiation, but second also on our visual perception system. After a rough comparison of ranges in water, glass, and the atmosphere, we focus on the physical basis of visual range for the latter. As a contrast phenomenon, visual range refers to allowed light paths within the atmosphere. It results from the interplay of geometry, refraction, and light scattering. We present a concise overview of this field by qualitative descriptions and quantitative estimates as well as classroom demonstration experiments. The starting point is the common geometrical visual ranges, followed by extensions due to refraction and limitations due to contrast, which depend on scattering and absorption processes within the atmosphere. The quantitative discussion of scattering is very helpful to easily understand the huge ranges in nature from meters in dense fog to hundreds of kilometers in clear atmospheres. Extreme visual ranges from about 300 km to above 500 km require optimal atmospheric conditions, cleverly chosen locations and times, and a sophisticated topography analysis. Even longer visual ranges are possible when looking through the vertical atmosphere. From the ISS, daytime ranges well above 1000 km are possible. Y1 - 2025 U6 - https://doi.org/10.1088/1361-6404/adc4a0 VL - 46 IS - 3 PB - IOP Science ER - TY - JOUR A1 - Vollmer, Michael T1 - How many stars appear colored to the naked eye? JF - Applied Optics N2 - Naked eye studies of the clear night sky reveal that a certain percentage of all observable stars can be perceived as having color. Subjective estimates differ widely, ranging from just a few to a maximum of above two hundred. Explanations are based on the emission spectra of the stars, which are modified by interstellar dust clouds, the Earth atmosphere, and mostly the inverse square law. Color changes occur not only for variation of the star’s angular elevation above the horizon, but as well for decreasing nighttime sky brightness due to the transition from photopic via mesopic to scotopic vision. The maximum number of stars showing color to the naked eye depends on star illuminances on Earth and the background sky luminance. The limit of observing color is found to correspond to apparent visual magnitudes around , defining the number of colored stars. This also means that naked eye perception of stars with color is only possible for a certain star distance range, which is well below the maximum naked eye visual range of stars. Y1 - 2026 U6 - https://doi.org/10.1364/AO.580635 VL - 65 IS - 9 SP - C27 EP - C37 PB - Optica Publishing Group ER - TY - CHAP A1 - Vollmer, Michael T1 - Elektromagnetische Wellen – Grundlagen und ausgewählte Anwendungen T2 - Schwingungen und Wellen in Alltagskontexten N2 - Schwingungen und Wellen zeigen sich in vielen Alltagsphänomenen der Physik, d. h. in der Lebenswelt von Schülerinnen und Schülern. Dazu zählen in der Mechanik Beispiele wie Schaukeln, Seilwellen oder Wasserwellen am Strand, in der Akustik Schallwellen durch beliebige Geräusche oder stehende Wellen in Musikinstrumenten und im Elektromagnetismus die allgegenwärtigen elektromagnetischen Wellen. Letztere haben vielfältigste Anwendungen, z. B. Erhitzen mit Mikrowellengeräten, Kommunizieren mit Smartphones, Datenübertragung mit Lichtleitern oder Fotografieren mit Kameras, ganz zu schweigen von medizinischen Anwendungen der Endoskopie, des Röntgens oder laserbasierten chirurgischen Eingriffen. Viele dieser Anwendungen haben ein enormes Motivationspotenzial in der Lehre, weshalb das Thema fest in Lehrplänen der Sekundarstufen verankert ist. Im Folgenden werden zunächst allgemeine Grundlagen und Gemeinsamkeiten der Beschreibung beliebiger Wellen diskutiert, bevor das Hauptaugenmerk auf elektromagnetische Wellen und ausgewählte Anwendungen gelegt wird. Y1 - 2025 U6 - https://doi.org/10.1007/978-3-662-70949-8_3 SP - 35 EP - 48 PB - Springer ET - 1 ER - TY - JOUR A1 - Vollmer, Michael T1 - Optical Phenomena in the Atmosphere JF - Encyclopedia of Atmospheric Sciences N2 - Following a brief description of the atmosphere and spectra of the Sun as dominant daytime light source, the most common optical phenomena within the troposphere are discussed, which are due to scattering of radiation with the constituents of the atmosphere. At first mirages, rainbows, coronas, iridescence, glories and halos are explained. Then light scattering phenomena which give rise to sunset colors, blue and colorful skies are presented as well as related phenomena like blue mountains, white clouds, green flashes and visual ranges. The review ends with a short survey of other less easily observable optical phenomena of the atmosphere and a very detailed bibliography. Y1 - 2025 U6 - https://doi.org/10.1016/B978-0-323-96026-7.00177-6 IS - 2 SP - 285 EP - 306 PB - academic press ET - 3 ER - TY - BOOK A1 - Vollmer, Michael T1 - Optik und ihre Phänomene BT - Lichtspiele in der Natur: von Luftspiegelungen und Himmelsfarben bis in die Weiten des Alls N2 - Dieses Lehr-, Lern-, Fach- und Sachbuch präsentiert die Grundlagen der Optik in Theorie und ausführlich beschriebenem Experiment sowie vielfältige faszinierende optische Phänomene. Ob in Vorlesungen, Seminaren, für Projektarbeiten, Schulunterricht oder Selbststudium - dieses Buch ist eine wertvolle Ressource für alle, die sich für Optik interessieren. Durch die große Zahl zitierter Originalarbeiten schlägt es nicht nur die Brücke zur Lehre sondern auch zur Forschung. Y1 - 2024 SN - 978-3-662-69308-7 SN - 978-3-662-69309-4 U6 - https://doi.org/10.1007/978-3-662-69309-4 PB - Springer ET - 3 ER -