Sunshine related variables

Introduction

 
 

This section presents the analysis for:

 

Sunshine records are some of the longest duration meteorological data in the UK. Figure 40 (chapter 3) shows where the recording sites are located. Records of the number of hours of sunshine in a day have been kept since 1929. We present this information alongside the assessment of trends over the 1961 to 2004 period that we are using as the benchmark for this study. The maps show change in sunshine hours as a percentage. Because daylight hours are lowest in winter we only need to see a small change to result in a relatively large percentage change.

 

We have also analysed information on cloud cover in this handbook. Recording methods for hours of sunshine and cloud cover mean that there is no direct relationship between the two. However, it is reasonable to assume some kind of correlation between the two. But the information on cloud cover should be treated with some caution. The large-scale move to automated observing methods over recent years means that we cannot assume that the values have been consistently measured. Any trend may be due to the change in recording method rather than any real change in cloud cover.