Our climate and weather patterns are caused by a complex combination of effects from uneven heating by the Sun, wind patterns, Earth’s rotation, and Earth's axial tilt or obliquity. This is a rather simplistic statement, but all the other factors that drive our climate and weather result directly or indirectly from these processes.
Radiant energy from the Sun is more concentrated in the equatorial region and the resultant heat tends to warm the air and cause it to rise, releasing moisture in the process, and move both northward and southward at high elevation towards the poles. Along the way, it cools and much of it sinks back toward the surface as dry, cool air (causing high pressure zones near the surface around the 30° Latitudes). Some of this air returns toward the equatorial region creating easterly trade winds near the surface and some of it moves into temperate zones creating westerlies near the surface. These eastward and westward surface wind movements are driven by the rotation of the Earth, and in addition, the Coreolis Effect causes surface winds and currents to bend to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This what maintains the circulating oceanic currents (clockwise movements in the Northern Hemisphere and counterclockwise movements in the Southern Hemisphere), and explains why the North Atlantic Drift brings warmer water to the coast of Svalbard.
The Earth’s obliquity causes our seasons, because the 23.5° tilt relative to Earth’s plane of revolution around the sun means the northern hemisphere faces more directly toward the Sun during Summer moths (the radiant energy is more concentrated per surface area) and away from the Sun during Winter months. This effect is most extreme in the polar regions, where one encounters up to 24 hrs/day of sunlight in the Summer and up to 24 hrs/day of darkness in the Winter. The rotational poles will actually encounter six months of sunlight, followed by six months of no view of the sun.
Insofar as Svalbard is concerned, most of the weather and climate data is collected at or near Longyearbyen. Because of its extreme northern location (78º 13′ N), Longyearbyen experiences a polar day that lasts from April 19 to August 23. The Sun does not rise above the horizon from October 28 to February 14, and the official polar night (when the Sun remains more than 6 degrees below the horizon) lasts from November 14 to January 29. The climate is fairly typical for a polar region, in that the Summer is quite cool (the average temperature in July is 5°C or 41°F) and the Winter is long and bitterly cold (the average temperature in February is -12°C or 10°F). Longyearbyen receives about 300 mm (12 in) of precipitation per year, most of which falls as snow.
The relatively warm North Atlantic Drift moderates Svalbard's climate considerably, especially near the western coast. Most of the surrounding waters do not freeze and remain open and navigable for much of the year. However, pack ice that has formed farther north has a tendency to drift into eastern island waters during the summer. In fact, Winter in Longyearbyen averages about 20 degrees warmer than similar latitudes in other parts of the world.
Join us for updates, insider reports & special offers.