latitude variation

Latitude variation is the small semi-cyclic apparent change in the declinations of stars due to the Chandler wobble and fluctuations in atmospheric refraction. Earth's polar wandering causes a maximum variation of 0.36 arcsecond (equivalent to a latitude shift of about 10 meters on the ground) in a period of 432 days. Seasonal movements of air masses result in an additional variation of 0.18 arcsecond ( +/-5 meters) in a period of one year.