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As well as characterising the baseline climate, there are available data that can be used to identify recent historic trends in climate, as measured at various locations across the region. In this section, we have:
This analysis yields the following main findings through comparison of the 1970s and 1980s baselines and longer-term data records:
Baseline data gathered from the Met Office at specific stations within the region has allowed us to depict changes between the 1961–1990 (the 1970s) baseline and 1971–2000 (the 1980s) baseline, as defined by the Met Office. Available data provides detail on maximum and minimum temperatures; days of air frost; sunshine and rainfall. Locations within the Yorkshire and Humber region with available data for both the 1970s and 1980s are:
Data are presented in tables and graphs for each of these three stations.
Sheffield Table 1: Sheffield Averages (a) 1961-1990 (the 1970s) (b) 1971-2000 (the 1980s)
Graph 1: Sheffield Average Temperature
For both the minimum and the maximum temperatures on graph 1, there is a clear visible rise in temperature. This temperature rise can be between 0.2 ˚C and 0.5˚C with values peaking at 20.8˚C during July of the 1980s.
Graph 2: Sheffield Average Hours of Sunshine
Inherently linked to the temperature increases over the two periods, are the number of sunshine hours received in Sheffield. There is a marked difference in the summer months with both July and August receiving approximately 20 hours more sunshine in the 1980s than in the 1970s. The winter months averages remain similar.
Graph 3: Sheffield Average Rainfall
The rainfall statistics received from the Met Office website are more varied. Overall, there is less rain received in the 1980s than the 1970s. However, the months of January, June, October and December received an increased amount of rainfall at the station.
Graph 4: Sheffield Average Number of Days Air Frost
The number of days of air frost gives a good indication of the air temperature and the convection of heat between the air and land. The overall trend in Sheffield shows a decrease in the number of days with air frost during the winter and spring months from the 1970s to the 1980s. The summer months remain the same with no air frost days recorded.
Cleethorpes Table 2: Cleethorpes Averages (a) 1961-1990 (the 1970s) (b) 1971-2000 (the 1980s)
Graph 5: Cleethorpes Average Temperature
As with Sheffield, graph 5 demonstrates the increase in temperature over the two periods. The annual average shows an overall increase in temperature of 0.3˚C.
Graph 6: Cleethorpes Average Hours of Sunshine
The hours of sunshine received by Cleethorpes, a coastal town, only varies in the summer months when May, July and August receive more sunshine in the 1980s than in the 1970s. all other months have similar figures in both sets of data and only June received less sunshine in the 1980s than in the 1970s.
Graph 7: Cleethorpes Average Rainfall
Rainfall is again very sporadic. There are months where more rainfall occurs than others. Annual averages show that 1mm less rainfall was recorded in the 1980s. A slightly warmer climate could be an inducer of less rainfall but with only a 1mm annual difference between the 2 data sets.
Graph 8: Cleethorpes Average Number of Days Air Frost
Air frost days, being an indicator of the air temperature and temperature inversions, show temperature changes. The graph above shows that there are less days of air frost in the 1980s than in the 1970s during the colder months from November to March. The summer months are unaffected by the number of days with air frost.
High Mowthorpe Below are the averages taken from the Met Office website for High Mowthorpe. This weather station is situated in a village near the Vale of Pickering, close to the town of Malton, North Yorkshire. This location is a good comparison to both Sheffield and Cleethorpes being rural compared to a seaside resort and an industrial city. Table 3: High Mowthorpe Averages (a) 1961-1990 (the 1970s) (b) 1971-2000 (the 1980s)
Graph 9: High Mowthorpe Average Temperature
As expected, temperatures have risen between the two time periods of the 1970s and the 1980s. Annual averages have risen by 0.3˚C overall. The summer months of July and August and the winter months from November to March see the greatest increase in temperatures.
Graph 10: High Mowthorpe Average Hours of Sunshine
The sunshine days in High Mowthorpe have increased between the 1970s and the 1980s with the exception of June. As with before, the summer months show a greater increase in the sunshine hours, specifically in July and August.
Graph 11: High Mowthorpe Average Rainfall
The rainfall statistics are as varied as those previous. Overall, it appears that less rainfall has fallen in the 1980s than the 1970s. The months of April, June, October and December received more rainfall. Annual averages show that the overall rainfall for the periods used, the 1980s received 11mm less rain that the 1970s.
Graph 12: High Mowthorpe Average Number of Days Air Frost
The number of air frost days is reduced from the 1970s to the 1980s. This demonstrates warmer air temperatures in the region. The summer months are unaffected by these results.
UKCIP08 Report The 11 variables listed below were used by UKCIP08 to gather information on the overall long-term climate trends in the report The Climate of the UK and Recent Trends. Those with an asterix are comparative to the data provided by the Met Office in the Baseline Climate section:
The changes in climate trends are illustrated in a number of ways ranging from maps, trend graphs and tables. From the information available in the report, it is possible to generate a general overview of changes in the baseline climate. Temperature Days of Air Frost Heating Degree Days Cooling Degree Days Precipitation/ Days of Rain ≥1mm Sea-level Pressure Wind Speed at 10m Relative Humidity
Historic Station DataAlso available from the Met Office is historic data from stations, with records running from the late 1800s. These stations provide data on the mean, maximum and minimum temperatures; days of air frost; rainfall and sunshine hours. The stations relevant to the study are: For the purposes of the present analysis, data from a single year has been recovered from every successive decade from the dataset. Bradford Graph 1: Bradford 100 year Maximum Temperature
The maximum average temperature for Bradford shows an overall increase in temperature over the 100 year period. Interestingly, the years with the lowest maximum temperature appear to have the greatest temperature range throughout the year. The year 1940 has both the lowest temperature in January and the highest temperature in June. Overall, the warmest year on the record for the winter months is 2000, showing that the climate over the 100 year period has increased in temperature despite not reaching the highest maximum average temperatures on the overall record.
Graph 2: Bradford 100 year Minimum Temperature
The average minimum temperature over the record show similar results to the maximum temperature above. 1940 has the lowest temperature in the winter months but also the highest temperature in August. The temperature increases over the 100 years are evident with the years 1990 and 2000 recording the highest winter averages and remaining high in the summer months.
Graph 3: Bradford 100 year Hours of Sunshine
The sunshine days are representative of the temperatures recorded. 1940 stands out as the year with the least sunshine in the winter but most in the summer. Interestingly, the warmer years of 1990 and 2000 have an average number of sunshine days. This may indicate an increased level of cloud cover, increasing the radiation received by the earth but less is reflected back into the atmosphere due to cloud reflecting the waves back to the earth’s surface.
Graph 4: Bradford 100 year Rainfal
Rainfall varies from year to year. The year 2000 was one of the driest summers on record. The year 1940 where temperatures have had the greatest variation, consistently received less than 100mm of rainfall through the year with only November reaching nearly 150mm.
Graph 5: Bradford 100 year Number of Days Air Fros
The number has days air frost has decreased over the 100 year period. Evidently the summer is unaffected by the air frost record. The lower number of frost days is lower in the latter half of the century with the year 2000 being consistently low. Fewer air frost days represent warmer temperatures and less variation between the temperatures on the earth’s surface and in the lower troposphere.
Graph 6: Sheffield 100 year Maximum Temperature
An overall increase in temperature through the 100 year period identified demonstrates an overall warming of the air temperatures in Sheffield. 1940 shows the greatest temperature range from the winter through to the summer with the coldest winter and the warmest summer. The latter years of 1990 and 2000 are consistently higher throughout the year with 1990 peaking at approximately 23˚C in August. Interestingly, 1920 recorded the warmest winter months but the coolest summer months.
Graph 7: Sheffield 100 year Minimum Temperature
The minimum temperature variations show a clear result of temperature rise over the century. 1940 again has the greatest range in temperature over the year. However, there is a clear distinction of 1990 and 2000 for having the highest minimum temperatures during the winter months and with the exception of 1900, the warmest summer month temperatures.
Graph 8: Sheffield 100 year Hours of Sunshine
The record the number of hours of sunshine received in Sheffield only runs from 1930. Therefore, we have a 77 year record. From this, it is possible to see the significance of 1940 with the low number of hour’s sun in the winter and receiving the most sunshine days in June. 1990 has a similar range to that of 1940 but 2000 received a comparatively lower number of hour’s sunshine. This can be explained through increased cloud cover increasing temperatures due to increased reflection of heat by the clouds down to the earth’s surface.
Graph 9: Sheffield 100 year Rainfall
The graph can demonstrate that the latter years of the century generally recorded less rainfall. Overall, the general trend in rainfall decreases over the years indicating a change of the baseline climate.
Graph 10: Sheffield 100 year Number of Days Air Frost
The number of days with air frost decreases over the 100 year period identified. The years 1890 and 1940 stand out with the most days of air frost and the later years having significantly less air frost days and therefore less temperature difference in the surface and air temperature that instigates air frost.
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