Earth’s Motion and the Atmosphere

Rotates Rotates around its axis. Revolves Revolves around the Sun. Revolves Revolves with the Solar System, around the center of our Milky Way galaxy. Moves Moves with the galaxy, out from the Big Bang origination point (wherever that is…) Precesses It also Precesses ! The Earth:

Precession The direction that the Earth’s Axis points changes gradually, in a circular pattern, every 26,000 years. It precesses – or spins a little off-center - like a top.

Polaris Currently our true North Pole points toward Polaris, our current “North Star.” Vega, In 14,000 AD it will point at Vega, in the constellation Lyra. Thuban, in the constellation Draco 5,000 years ago it pointed at Thuban, in the constellation Draco.

Earth’s Rotation… Earth rotates once every 23 hrs 56 min. Tangential Velocity varies But the Tangential Velocity (The instantaneous linear velocity of a body moving in a circular path – think of it as the location’s speed) varies with latitude. Its speed is about… 1000 mph at the Equator, 1000 mph at the Equator, 800 mph here in Culver City, 800 mph here in Culver City, 0 mph at the poles. 0 mph at the poles.

The Coriolis Effect Due to Earth’s rotation an object trying to go directly from Pole to Equator will be deflected to the West. (An object going from Equator to Pole will be deflected to the East.) This causes…

…ocean currents to circle clockwise in the Northern Hemisphere… (counterclockwise in the southern)

Storms to circle counterclockwise in the northern hemisphere, Clockwise in the southern…

Atmospheric Convection Currents are deflected into prevailing winds, which divide the atmosphere into bands moving in alternate directions.