Solar cycle

solar cycle

The approximately 11-yr quasi-periodic variation in the sunspot number. Sunspots begin appearing at higher solar latitudes as a cycle begins and slowly drift more equatorward, becoming more in number and larger, more complex groups as the cycle draws to solar maximum. As the cycle moves to solar minimum, sunspot development slows and locations become more sporadic, eventually going days to months without any visible sunspots. The magnetic polarity pattern associated with sunspot groups in each hemisphere will reverse at the beginning of a new solar cycle. Solar cycles are numbered, beginning with solar cycle 1 in 1755. A more recent case was cycle 24 which began in 2008 (minimum) and peaked in 2014 (maximum).

Space Weather Prediction Center, 2018: Sunspots/solar cycle. Accessed 1 October 2018. Available at https://www.swpc.noaa.gov/phenomena/sunspotssolar-cycle.

Term edited 1 October 2018.

1. The effect of the velocity of fluid flow upon the velocity (relative to a fixed external point) of an object moving within the fluid; the vector difference between the velocity of the object relative to the fluid and its velocity relative to the fixed reference.

See numerical weather prediction, climate prediction;

A relatively dark area on the surface of the sun consisting of a dark central umbra surrounded by a penumbra, which is intermediate in brightness between the umbra and the surrounding photosphere.