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In planar dynamics a pole is a center of rotation, the polar is the force line of action and the conic is the mass–inertia matrix. [4] The pole–polar relationship is used to define the center of percussion of a planar rigid body. If the pole is the hinge point, then the polar is the percussion line of action as described in planar screw theory.
Visualization of the ice and snow covering Earth's northern and southern polar regions Northern Hemisphere permafrost (permanently frozen ground) in purple. The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles.
The reference point (analogous to the origin of a Cartesian coordinate system) is called the pole, and the ray from the pole in the reference direction is the polar axis. The distance from the pole is called the radial coordinate, radial distance or simply radius, and the angle is called the angular coordinate, polar angle, or azimuth. [1]
Polar point group, a symmetry in geometry and crystallography; Pole and polar (a point and a line), a construction in geometry Polar cone; Polar coordinate system, uses a central point and angles; Polar curve (a point and a curve), a generalization of a point and a line; Polar set, with respect to a bilinear pairing of vector spaces
Polar bears are believed to travel rarely beyond about 82° North, owing to the scarcity of food, though tracks have been seen in the vicinity of the North Pole, and a 2006 expedition reported sighting a polar bear just 1 mi (1.6 km) from the Pole.
Relationship of Earth's axial tilt (ε) to the tropical and polar circles. The Arctic Circle is the southernmost latitude in the Northern Hemisphere at which the centre of the Sun can remain continuously above or below the horizon for twenty-four hours; as a result, at least once each year at any location within the Arctic Circle the centre of the Sun is visible at local midnight, and at least ...
The polar vortex is a whirling cone of low pressure over the poles that's strongest in the winter months due to the increased temperature contrast between the polar regions and the mid-latitudes ...
The latitude of the polar circles is + or −90 degrees (which refers to the North and South Pole, respectively) minus the axial tilt (that is, of the Earth's axis of daily rotation relative to the ecliptic, the plane of the Earth's orbit). This predominant, average tilt of the Earth varies slightly, a phenomenon described as nutation.