Observations/Arctic vs Antarctic Winter

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Arctic vs Antarctic Winter

We're going to explore the differences between Arctic and Antarctic Winter. In the winter time at the Arctic and Antarctic regions, there's said to be a long period of time where the sun never shows - darkness.

It is important to understand night time and day time when it comes to darkness, Twilight, daylight, and sunlight. these terms will be used throughout this article:

  • Sunlight: When the sun is visible in the sky.
  • Daylight: Daylight is the combination of all direct and indirect sunlight during the daytime. When the sky has light, and the sun has not moved "below" or beyond our apparent horizon.
  • Twilight: the sky is illuminated to some extent whenever the sun's upper rim is less than 18-degrees "below" or beyond our apparent horizon.
  • Darkness: After the sun has moved 18-degree "below" the apparent horizon, marks the limit of astronomical twilight, when the sky is indeed totally dark from horizon to horizon.

Arctic Winter

Weather and climate in Arctic

The Arctic consists of ocean that is largely surrounded by land. As such, the climate of much of the Arctic is moderated by the ocean water, which can never have a temperature below −2 °C (28 °F). In winter, this relatively warm water, even though covered with ice, keeps the North Pole from being the coldest place in the Northern Hemisphere. This is also why it's claimed to be the reason that Antarctica is so much colder than the Arctic.

The lowest officially recorded temperatures is −67.7 °C (−89.9 °F) which occurred in Oymyakon, Russia on 6 February 1933.

In the warmest months

June to August

  • Near the ocean: average temperatures hover around 10 °C (50 °F).
  • Interior regions: temperatures can reach 30 °C (86 °F) or higher

The coldest months

January and February

  • The interior regions: temperatures are lower than −45 to −30 °C (−49 to −22 °F)

Darkness

Certain myths die hard. One of these myths is that the entire Arctic region experiences six months of daylight and six months of darkness. Often times, "night" is simply considered to be when the sun is beneath the horizon, as if twilight didn't exist.

For a full six months out of the year, the North Pole does not see the Sun. However, it isn’t entirely dark during this time. As you likely know, even after the Sun has dipped below the horizon at the end of the day, it can remain light enough to do outside activities for a little while longer. The completely dark period of time on the North Pole lasts from about Nov. 13 to Jan. 29. [1]

North cape, the most northerly point of Norway (71° North), is in the shadow of the north pole. At that point you can see the "midnight sun" in all his ghastliness, that great luminary being constantly above the horizon from May 5 to Aug. 6, or just one day over three months. But the long wintry night makes up for this 100 days of constant sunshine. It begins on Sept. 22 and constantly increases in length until Nov. 6, when the 'polar night" commences in earnest, the sun never appearing above the horizon from the last mentioned date until Feb. 5, one day less than three months.

According to NOAA [2]

  • Winter - The darkest time of year at the North Pole is the Winter Solstice, approximately December 21. There has been no sunlight or even twilight since early October. The darkness lasts until the beginning of dawn in early March.
  • Spring - The sun rises at the North Pole on the Spring Equinox, approximately March 21, and the sun rises higher in the sky with each advancing day, reaching a maximum height at the Summer Solstice, approximately June 21.
  • Summer - In summertime, the sun is always above the horizon at the North Pole, circling the Pole once every day. It is highest in the sky at the Summer Solstice, after which it moves closer to the horizon, until it sinks below the horizon, at the Fall Equinox.
  • Autumn - At the Autumn Equinox, approximately September 21, the sun sinks below the horizon, and the North Pole is in twilight until early October, after which it is in full darkness for the Winter

Antarctic Winter

Surface temperature of Antarctica in winter and summer

Weather and climate in Antarctica

It is said the South Pole is colder than the North Pole because of it's different "geographical configuration" and altitude: owing to the huge ice sheet that covers the continent.

About 90% of the ice on earth is found in Antarctica.

The average altitude is around 2,000/2,400 meters (6,600/8,000 feet), with large areas above 3,000 meters (9,800 feet), so it is far higher than in the other continents.

There is air circulation that prevents the penetration of mild ocean winds towards the interior: both air and sea currents flow around the continent with an almost circular motion, from west to east (the so-called Antarctic Circumpolar Current). [3]

The coldest months

July and August

  • South Shetland Islands: the daily average is -5/-6 °C (21/23 °F)
  • Antarctic Peninsula: -10/-12 °C (10/14 °F)
  • coast surrounding Antarctica: -15/-18 °C (0/5 °F)
  • coldest areas of the plateau: it drops below -60 °C (-76 °F)

In the warmest months

December and January

  • South Shetland Islands: the daily average is 1/2 °C (34/35.5 °F)
  • Antarctic Peninsula: the daily average is 1/2 °C (34/35.5 °F)
  • coast surrounding Antarctica: it ranges from -2 to +2 °C (28.5 to 35.5 °F)
  • coldest areas of the plateau: drops below -30 °C (-22 °F)

Darkness

In the The Belgica expedition (1897-1899) people got the impression that they were going to make a search for the South Pole. This is wrong. The purpose instead was to make a scientific survey and to study the fauna and flora of the Antarctic region. However, more significantly, this was the first documented expedition of human beings spending the winter in Antarctica.

The most distinctive feature about our expedition is the fact that we were the first human beings to ever spend a winter in the Antarctic circle.
- Frederick Cook 1899

"The antarctic night, which lasts for seventy one days at Cape Adair, is longer than the night at the same latitude in the north. Like an evil, sneaking spirit the antarctic night wraps the traveler in its black, cold clasp. No one who has not faced these midnight winters fully realizes what a depressing effect the lack of sunlight has upon the human mind.
- Borchgrevink 1900

From the historical references (See the section Further Reading) there were 63 - 71 days of total darkness during the Antarctic Winter (May to July).

Summaries

It seems we have statements saying the Southern Winters are longer than in their Northern counterpart latitudes, yet NOAA and others shows the north having longer Winters than in the south.

Temperature

Location Min (Avg) Max (Avg)
North −45 °C (−49 °F) 10 °C (50 °F)
South < -60 °C (-76 °F) -2 °C (28.5 °F)

Darkness

Expedition Date Event
90° North Pole Nov. 13 to Jan. 29 Darkness from early October until the beginning of dawn in early March: 77 days
71° North/North cape Nov. 6 to Feb. 5 'polar night' commences, one day less than three months (91 days), however Polar night also includes various stages of Twilight.
71° South/Belgica Mid May to July 22 The men gather at noon to witness the return of the sun for about 20 minutes after 63 days of "total darkness".
78° South/Borchgrevink 1898-1900 latitude 78.50, The antarctic night, which lasts for 71 days at Cape Adair, is longer than the night at the same latitude in the north.

Seasonal Variations of the Duration of Twilight

According to University of Toronto, Canada the following sets of charts are plotted from the day before March 1, 2007 to the day after March 31, 2008 to span a range of dates from before the northward equinox until after the next northward equinox — the charts would appear similar for other near-present-era years. The charts show the duration of dusk twilight but the duration of dawn twilight are essentially symmetrically equal for any given degree of solar depression angle.

If the duration of twilight is expressed in terms of mean solar minutes (normal clock time), then seasonal variations are evident for all locales, with the shortest twilight duration a few days before the spring equinox and a few days after the fall equinox, and the longest twilight duration near the summer solstice, with a lesser maximum of duration near the winter solstice.

The seasonal variation and duration of twilight is minimal at the equator, where the solar parallactic angle at the horizon is always 90°, and the variations increase in amplitude and duration for locales that are progressively further away from the equator.

See the referenced chart for these readings, these reading indicate a fairly equal twilight times in the North and South in their respective winters: [4]

Further Reading

We will state that the old theory of compensation for the shortness of the Southern summer by lesser distance from the sun, is now seriously questioned. Many savants claim that the southern hemisphere, instead of being warmer than the northern in similar latitudes, is shown by observation to be cooler.

There is nothing in the Southern Hemisphere to counterbalance this evident excess of weight in the Northern, except the Antarctic ice. But why should the Southern Polar Region contain more ice than the northern? The earth is now at its perihelion a little after the winter solstice, and travels over that portion of its orbit nearest the sun while the latter is South of the equator. When in this part of its orbit it moves faster than when in that part North of the equator, which is farthest from the sun. That is to say the earth makes faster time in going from the autumnal to the vernal equinox, than in going from the vernal to the autumnal. The difference amounts to about eight days, and the Southern Hemisphere has therefore eight days less of sunshine than the Northern.

Astronomers have not generally considered that the changes which effect the dates of perhelion and the Spring equinox namely, the- obliquity of the ecliptic and the greater rapidity or the earth in perihelion, would produce any material difference between the climate of the Northern and Southern hemispheres. When the earth is moving most rapidly in its orbit, it is also the nearest to the sun, and on the contrary when its motion is slowest, in apogee, it is at its greatest distance from the sun; thus the relative effects of the two positions compensate each other. In other words. although the summer of the southern hemisphere is shorter than that of the northern, it is, on account of its proximity to the sun, much warmer and receives during the year, demonstrably, as much heat as the northern. By this means the two differences are neutralized.

There is no doubt but what the astronomical changes, pointed out by M. Adhemar and elaborated by a recent writer in the Popular Science Monthly, do, to a certain extent, effect our climate; but those best qualified to form an opinion do not consider that such tremendous effects could be produced by the causes assigned.

Your correspondent "Cleon" appears to be under the impression that an excess of ice in the Antarctic regions is incompatible with the theory that the sun furnishes an equal amount of heat to both hemispheres; but a little investigation will show that such is not the case. The theory is that the amount of heat depends on the intensity multiplied by the time it is applied ; and the product of time and distance to the sun is the 6ame in either hemisphere. But it by no means follows that the physical effect of the sun's heat is the same in either hemisphere. It is not only a question as to the amount of heat received from the sun. It also involves an inquiry into the manner in which that heat performs its work.

The sun shines on the northern hemisphere about eight days longer than on the southern, consequently it is a little warmer on the earth while the sun is south of the equator than while it is north of it.

It is undeniable that the Antarctic region is colder than the arctic, whatever may be the cause;

...our northern hemisphere has 4464 hours of day in the year and 4296 hours at night, while the southern hemisphere has 4296 hours of day and 4404 hours at night. This giving 168 more hours to night to the Southern than to the northern hemisphere.

Gradually the days got shorter and shorter, dreary and more dreary. On May17 the sun set after a day ofonly a few minutes' duration, and we did not see it again for nearly ten weeks. Then began our struggle with ourselves. There was nothing we could do for days and days and the awful darkness bore down like a heavy weight.

Antarctic night came on in May and we were in darkness for seventy days. During that time every member of the party suffered from anemia, due to the excessive humidity of the night, to the lack of fresh food and to the continuous storms.

Dr. F. A. Cook, describing the effects of the long Antarctic night on the human body and mind, says that on the I exploring ship Belgiac. As the cold I night lengthened, all became pale "with a kind of greenish hue." The heart grew feeble in its action. The men were incapable of concentrated thought. One sailor was driven to the verge of insanity, but when the returning sun began to reappear above the horizon he recovered.

The Antarctic night, which lasts for seventy-one days at Cape Adair, is longer than the night at the same latitude in the north.

Generally speaking we figure Europe as being wholly within the temperate zone, but when we come to investigate matters we find that North cape, the most northerly point of Norway, is in the shadow of the north pole. At that point you can see the "midnight sun" in all his ghastliness, that great luminary being constantly above the horizon from May 5 to Aug. 6, or just one day over three months. But the long wintry night makes up for this 100 days of constant sunshine. It begins on Sept. 22 and constantly increases in length until Nov. 6, when the 'polar night" commences in ear nest, the sun never appearing above the horizon from the last mentioned date until Feb. 5, one day less than three months.—St. Louis Republic.

See Also

References