Our Dynamic Weather
|Dr. Dave Dempsey
Dept. of Geosciences
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The latitude of any particular location on earth is defined as the angle (expressed in degrees and measured from the center of the earth) between that location and the equator.
The latitude of the equator itself is 0°. The angle between the North Pole and the equator is 90° (a right angle), so the latitude of the North Pole is 90° (the maximum possible latitude). The same is true of the South Pole.
The farther you are from the equator, the greater your latitude will be. Hence, latitude is a measure of distance from the equator.
To distinguish latitudes north of the equator (i.e., in the Northern Hemisphere) from those south of the equator (in the Southern Hemisphere), an "N" or "S" is attached to the latitude. For example, San Francisco lies at approximately 37.6°N latitude.
In a particular hemisphere, all of the places that lie equally far from the equator (and hence have the same latitude) define a circle, called a latitude circle. Latitude circles are parallel to each other and to the equator (which is just another latitude circle) and are smaller the farther they are from the equator. The North and South Poles are just latitude circles with zero radius—that is, points.
Meteorologically Significant Latitude Zones
Meteorologically significant latitude zones (see Figure 1) include the following:
As a broad generalization, the nature of the weather and climate differs in significant ways between each of these three latitude zones, though it can differ greatly within them too.
Astronomically Defined Latitude Zones
Other meteorologically significant latitude zones, partly overlapping with those above, can be defined in terms of astronomically significant latitudes (see Figure 2), which are associated with the orientation of the earth's axis of rotation relative to the sun and how that orientation varies as the earth revolves around the sun over the course of the year (giving rise to the seasons). Astronomically significant latitudes include:
Meteorologically significant latitude zones defined at least partly by these astronomically significant latitudes include: