Analysis of Extreme Temperatures in the Central England Temperature (CET) Thermometer Record (IMAGE)
Caption
Analysis of extreme temperatures in the Central England Temperature (CET) thermometer record.
Part (b) shows the lowest monthly average in each winter whereas part (c) shows the hottest monthly average in each summer. In both cases blue shows lower temperatures, and red shows higher temperatures than the long-term average.
The cold winter months match up very well with the years in which frost fairs were held (vertical mauve lines) or years when the Thames was reported as frozen solid (vertical orange lines). However these years are not usually also associated with colder summers, unless there was a large volcanic eruption (measured from the sulphates that it deposited in polar ice sheets) such as Tambora in 1815.
The top panel (a) shows the level of solar activity as seen in sunspot numbers (from telescopic observations and deduced from Carbon-14 stored in tree rings). It can be seen that, contrary to common claims, the Thames did not freeze more often during the Maunder minimum (c.1660-1710). Thames freezing events ceased after the demolition of the old London bridge in 1825 and the installation of the embankments, completed in 1870 (both dates marked with black lines): the faster flow meant that the river no longer froze, even when temperatures fell to values that had previously caused freezing.
Credit
M. Lockwood
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