Irish dance (typically the top half of dancers graded after the first two rounds) of dancers are invited back to perform. The Céilí dances used in competitions are more precise versions of those danced in less formal settings. There is a list of 30 Céilí dances which have been standardised and published in An Coimisiún's "Ar Rinncidhe Foirne" as examples of typical Irish folk dances; these are called the "book" dances by competitive stepdancers. Most Irish dancing competitions only ask for a short piece of any given dance, in the interests of time. There are two types of shoes; soft shoes (also
Solar activity and climate the measurements started in 1978. Solar irradiance before the 1970s is estimated using proxy variables, such as tree rings, the number of sunspots, and the abundances of cosmogenic isotopes such as Be, all of which are calibrated to the post-1978 direct measurements. Solar activity has been on a declining trend since the 1960s, as indicated by solar cycles 19-24, in which the maximum number of sunspots were 201, 111, 165, 159, 121 and 82, respectively. In the three decades following 1978, the combination of solar and volcanic activity is estimated to have had a slight cooling influence. A 2010 study