The polar night is the night lasting more than 24 hours, usually inside the polar circles. The opposite phenomenon, when the sun stays above the horizon for a long time is called the polar day, or midnight sun. The effect is so significant that the Finnish language has a word, kaamos, which specifically refers to the polar night. Melbourne skyline at night Night or nighttime is the period in which the sun is below the horizon. ... The hour (symbol: h) is a unit of time. ... The polar circles is a name for the Arctic and the Antarctic Circle. ... See the section Popular culture below for novels and other popular culture related to the Midnight Sun. ... Finnish ( ) is the language spoken by the majority of the population in Finland (92%[1]) and by ethnic Finns outside Finland. ...

A common misunderstanding is that at each point inside the polar circle, or that at each place where midnight sun occurs, the shortest day is totally dark. Because of twilight, this is not the case. In places very close to the poles this is true, but in areas very close to the arctic and antarctic circle, midnight sun is experienced, but polar night is never experienced. In fact, polar regions typically get more light throughout the year than regions located closer to the equator. Twilight in Denmark, just after sunset Twilight in the midwestern US featuring Venus as a brilliant evening star and the crescent moon Finland - Lapland at midnight in July Twilight in Acapulco with Long time Exposure Twilight is the time before sunrise or after sunset when sunlight scattered in the upper... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ...

In regions inside the polar circles, the length of the time when the sun is below the horizon varies from 20 hours at the Arctic Circle and Antarctic Circle to 179 days at the Poles. However not all this time is classified as polar night, since there may be plenty of sunlight because of refraction. Also, one might notice that the time above the horizon at the poles is said to be 186 days. The asymmetry in numbers is because the time when the sun is partially above the horizon is counted towards the "daytime". Zoomable PDF of the map this is based on The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. ... The straw seems to be broken, due to refraction of light as it emerges into the air. ...

Kinds of polar night

Various kinds of polar night exist. This is because polar night is the period during which no twilight occurs; but there are various kinds of twilight. Twilight in Denmark, just after sunset Twilight in the midwestern US featuring Venus as a brilliant evening star and the crescent moon Finland - Lapland at midnight in July Twilight in Acapulco with Long time Exposure Twilight is the time before sunrise or after sunset when sunlight scattered in the upper...

Civil polar night

The civil polar night is the period during which no civil twilight occurs. Civil twilight happens when the sun is between zero and six degrees below the horizon. Because of refraction, there still is enough light for normal outdoor activities. Civil polar night is limited to latitudes above 72° 33′, which is exactly six degrees inside the polar circle. In mainland Europe, there are no places fulfilling this definition. Civil twilight is when the Sun is 6 degrees or less below the horizon. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength[1]. The elementary particle that defines light is the photon. ... This article is 150 kilobytes or more in size. ...

Nautical polar night

The nautical polar night is the period during which there is only a faint glow of light visible during midday. It happens when there is no nautical twilight. Nautical twilight happens when the sun is between six and twelve degrees below the horizon. Because of refraction, there is still a place at the horizon with clearly more light than other places. The nautical polar night is limited to latitudes above 78° 33′, which is exactly 12 degrees within the polar circle, or eleven and a half degrees from the pole. It has been suggested that this article or section be merged with Dawn. ... Horizon. ...

Astronomical polar night

Finally, the astronomical polar night is the period that no trace of light can be seen anywhere and no astronomical twilight occurs. Astronomical twilight happens when the sun is between twelve and eighteen degrees below the horizon. Thus, astronomical polar night happens at latitudes above 84° 33′, which is exactly 18 degrees within the polar circle, or five and a half degrees from the pole. Twilight in Denmark, just after sunset Twilight is the time before sunrise and after sunset when sunlight reflected from particles in the upper atmosphere illuminates the lower atmosphere and the surface of the earth. ...

There are no permanent settlements anywhere in this range of latitude. This portion of the Arctic Ocean is generally permanently ice capped. Some scientific stations in Antarctica, including Amundsen-Scott at the South Pole, experience this. The Amundsen-Scott South Pole Station is a U.S. research station at the South Pole, in Antarctica. ... Amundsen-Scott South Pole Station. ...

Effects on humans

The period of polar night can trigger depression in some people. Polar days may affect people as well. People who suffer from seasonal affective disorder are particularly susceptible. Polar night may also be implicated in some instances of solipsism syndrome. Clinical depression (also called major depressive disorder, or sometimes unipolar when compared with bipolar disorder) is a state of intense sadness, melancholia or despair that has advanced to the point of being disruptive to an individuals social functioning and/or activities of daily living. ... The midnight sun at Nordkapp, Norway The midnight sun is a phenomenon, occurring in latitudes north of the arctic circle and south of the antarctic circle, where the sun is visible during at least 24 hours. ... Seasonal affective disorder, or SAD, also known as winter depression is an affective, or mood, disorder. ... Some environments are conducive to the state of mind, known as Solipsism Syndrome, in which a person feels that everything is a dream and is not real. ...

External links

• Polar night and polar darkness
• Many years' of webcam pictures from Tromso, Norway. These clearly show the progression into and away from Winter at a latitude within the Arctic Circle.