Solstice | EPFL Graph Search

A solstice is an event that occurs when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21. In many countries, the seasons of the year are determined by the solstices and the equinoxes. The term solstice can also be used in a broader sense, as the day when this occurs. The day of a solstice in either hemisphere has either the most sunlight of the year (summer solstice) or the least sunlight of the year (winter solstice) for any place other than the Equator. Alternative terms, with no ambiguity as to which hemisphere is the context, are "June solstice" and "December solstice", referring to the months in which they take place every year. The word solstice is derived from the Latin sol ("sun") and sistere ("to stand still"), because at the solstices, the Sun's declination appears to "stand still"; that is, the seasonal movement of the Sun's daily path (as seen from Earth) pauses at a northern or southern limit before reversing direction. For an observer at the North Pole, the Sun reaches the highest position in the sky once a year in June. The day this occurs is called the June solstice day. Similarly, for an observer on the South Pole, the Sun reaches the highest position on the December solstice day. When it is the summer solstice at one Pole, it is the winter solstice on the other. The Sun's westerly motion never ceases as Earth is continually in rotation. However, the Sun's motion in declination comes to a stop at the moment of solstice. In that sense, solstice means "sun-standing". This modern scientific word descends from a Latin scientific word in use in the late Roman Republic of the 1st century BC: solstitium. Pliny uses it a number of times in his Natural History with a similar meaning that it has today. It contains two Latin-language morphemes, sol, "sun", and -stitium, "stoppage". The Romans used "standing" to refer to a component of the relative velocity of the Sun as it is observed in the sky.

Towards novel glazing with seasonal dynamics based on micro compound parabolic concentrators

André Gabriel Kostro, Josef Andreas Schuler, Jing Gong

Thermal loss and overheating caused by glazing is a key issue in reducing CO2 emission and energy consumption of buildings. A novel glazing based on micro compound parabolic concentrators (CPCs) is proposed. The glazing consists of a polymer layer with emb ...

2018

Potential advantages of a multifunctional complex fenestration system with embedded micro-mirrors in daylighting

Andreas Schueler, André Gabriel Kostro, Ali Motamed, Jing Gong

Proper daylighting designs in interior spaces may reduce the energy costs of electric lighting and improve the productivity of occupants. This paper reports the potential advantages of a multifunctional complex fenestration system with embedded micro-mirro ...

Pergamon-Elsevier Science Ltd2016

The Dynamics of Shadow: Architecture of Natural Light in Extreme Latitudes

Marilyne Andersen, Mandana Sarey Khanie, María Lovísa Ámundadóttir, Siobhan Francois Rockcastle

While architecture is composed of static structural elements, daylit space is perceived as a dynamic play of light and shadow – ephemeral qualities that add depth, texture, and movement to spatial composition. Our perception of architecture is greatly impa ...

2015