It also marks latitude and the role migratory birds play in H5N1 dispersal.
I looked at the map and the line that marked a latitude of 66 degrees 33 minutes — the Arctic Circle.
The Tropic of Capricorn is the circle marking the latitude 23.5 degrees south where the sun is directly overhead at noon on December 21, the beginning of winter in the northern hemisphere.
The Tropic of Cancer is the circle marking the latitude 23.5 degrees north, where the sun is directly overhead at noon on June 21, the beginning of summer in the northern hemisphere.
Two spotters accompanied the pilot to record the number of whale sharks observed, to take aerial photographs, and to mark the latitude and longitude of each sighting with a GPS data-logger.
The concentric dashed circles represent 10° increments of magnetic latitude, marked at 60°, 70° and 80°.
It has a sparse population, scattered over a very large geographic area; climate and latitude marked by seasonal extremes of temperature and daylight; and a spirited history of cross-border cooperation on issues of concern to Arctic peoples.
More CO₂ means oceans everywhere are becoming more acidic, but the phenomenon is particularly marked at high latitudes because cold water absorbs CO₂ more readily than warm water does.
In latitudes marked by distinct seasons, a seasonal thermocline at much shallower depths forms during the summer as a result of solar heating, and it is destroyed by diminished insolation and increased surface turbulence during the winter.
THE climatic warming trend since the 1880s (refs. 1 5), which seems to have been global in extent and was manifested by an upward trend in mean annual (and particularly mean winter) temperatures, seems to have given way since the 1940s to a cooling trend6, which is most marked in higher latitudes (> 60° N, refs. 7 and 8).
b Temporal variations of TEC reductions measured at the fixed IPPs from higher to lower latitudes (marked by blue dots in panel a).
