The physical background

• Main Author: Fogg, G E
• Format: Book Part
• Language: unknown
• Published: Oxford University PressOxford 1998
• Subjects: polar night; midnight sun
• Online Access: http://dx.doi.org/10.1093/oso/9780198549543.003.0001; https://academic.oup.com/book/chapter-pdf/52366918/isbn-9780198549543-book-part-1.pdf

Abstract The severities and complexities of polar habitats stem from simple geometry: the axis of the earth’s rotation is not at right angles to the plane in which it orbits round the sun. As a result, the North and South Poles are tilted in turn towards the sun and, instead of having the daily alternation of day and night to which most of us are accustomed, have months of nightless summer followed by sunless winter. With all his ability to create his own environment man does not find it easy to cope with either midnight sun or a night of several months. To a greater or lesser extent other organisms also have problems in adapting to the polar night. Surprisingly, the frigid climate which we tend to think of as the most characteristic and hostile feature of the poles is not a necessary result of the smaller amount of solar radiation which they receive but has been brought about by interplay of secondary factors. It has not been the norm in the geological past. The varying input of radiant energy from the sun over the surface of the earth sets up circulations in the atmosphere and oceans, which, directed by forces produced by the earth’s rotation and by the positions of land masses, convey heat from one part to another. In the immediate geological past these factors have operated to cause ice to accumulate at the poles. At present, ice is a dominant feature in polar habitats and its manifold patterns of formation, structure, accumulation, and movement give rise to a wide variety of situations, some transient, others more lasting, in which organisms have established themselves. In some, conditions are so severe that life survives only in a dormant state. Others support a surprising variety, amount, and activity of living things. The nature of the environmental conditions in these habitats and the ways in which organisms adapt to them provide the subject matter of this book. However, before considering these biological aspects we must look at the general physical features of the polar regions.