2020 officially saw a record number of $1 billion weather and climate disasters.
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Something that must be considered when comparing historical records is the effect of differences in radiation shields compared to conventional Stevenson Screens. Smaller multi-layer shields can show differences of several degrees in times of high solar radiation and light winds. I know I'll get attacked for stating the above so let me show the data.
Compare Wednesday's max temperatures of the agrimet stations (small shield, first map) to those of the standard synoptic stations (Stevenson Screens, second map). The synoptic network is less dense but all stations are several degrees below the agrimet ones.
This study investigated the difference between a the two types of shield and found a large spike (2 - 2.5 degrees) in the smaller shield (Type A below) during early afternoon, when solar radiation was at its peak.
Between 1300 and 1500, when global solar radiation averaged 935 W m2 and wind speed 2 m/s, both the standard deviation and the range of temperature in the Stevenson screen were smaller than comparable values for the two commercial screens: 0.39 and 1.72 °C, respectively, compared with 0.51 and 2.42 °C for screen ‘type B’, and 0.65 and 3.16 °C for screen ‘type A’. The time lag is illustrated in Figure 10: following sunrise, temperature in the lightweight commercial screen increases more rapidly than in the Stevenson screen, resulting in a temperature difference of up to 2 °C.
For most of the day, temperatures from the Stevenson screen remain about 1.5 °C lower. As solar flux decreases in the afternoon, the lightweight screen cools more rapidly, and the temperature difference is eroded.
Statistical analysis may not always reveal the full extent of differences between the Stevenson screen and modern gill-type screens. Table II shows typical statistical values for temperatures recorded in the Stevenson screen, in the two commercial screens and in a mechanically aspirated double-barrelled shield used as a reference on a sunny day. with light but fairly constant winds of about 1–2 m/s. As in the previous experiment, there is no ‘absolute’ reference temperature. However, it was considered that an air speed of about 6m/s over both surfaces of the interior shell of the mechanically aspirated shield was sufficient to ensure that the temperature of this shell would be very close to that of the air, resulting in negligible radiant heat transfer from the environment.
Differences between the temperatures recorded in the different screens appear to be quite small – maximum, minimum and mean daily temperatures were about 0.3–0.5 °C higher in the naturally ventilated screens than in the mechanically aspirated one. Yet, as Figure 10 shows, the temperature error in screen ‘type A’ (defined as the difference relative to the aspirated, double-walled screen) was in fact not negligible for most of the day: it was greater than 1 °C for most of the sunshine hour, and exceeded 2 °C for part of the time.
With the proliferation of these newer automated weather stations and their use in setting records, it would stand to reason that an increasing trend in records being broken may result. Now Akrasia will no doubt fob this off as me "furiously backpeddalling", but for most of the year and in most places, these difference may not amount to much. But in extreme cases, that is where these differences will be highlighted.
But again, I'm sure the WMO know this and consider it in their records...
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I'm not sure records, past or present, prove anything either way though. We had a 10 day heatwave here in this country recently and no max temp records were broken, but the sheer duration of the heatwave was historically noteworthy.
Edit:
Compared to RTE
New heat record in Italy as anticyclone 'Lucifer' sweeps in
State funded media showing no bias at all there. 🤑 - Nabber.
Southern Italy was under a slack trough, not a luciferin Anticyclone when that temp was reached:
Media, eh?
New Moon
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