For Non-Experts: Some Definitions
Climatology refers to the field of climate science, but
within climate science it usually means a data set that has been
averaged over a number of years. For example, the climatology of
March temperatures is the average of every March during a certain time
period (the March temperature for a given year is itself an
average of measurements taken twice every day of the month). A
standard period for calculating climatologies is 30 years.
Anomaly is the difference of a particular value from its
climatological value. For example, here the March 2010 temperature
anomaly is the difference between March 2010 average temperature and
the average of all March temperatures from 1985 to 2014. Unlike in
common usage, "anomaly" does not mean "odd, unexpected"--in fact if
temperature one year had no anomalies it would be, well,
anomalous!
Running mean does not refer to kicking your competitors when
in a foot race, but is simply an averaging process that includes times
before and after each time. For instance, in a three month running
mean, "March 2010" is actually the average of February-March-April
2010, and "April 2010" is the average of March-April-May 2010.
