OPAL Climate Survey results

The OPAL Climate Survey ran from 2011 to 2014. We asked participants to undertake a number of activities relating to weather and climate - looking at aspects of cloud, winds, and temperature.

Here, in summary, is what we learned...


Contrails across blue sky

Contrails are clouds formed when water vapour condenses and freezes around small particles released from aircraft exhausts.

These contrails may be a contributing factor in climate change. It's thought that aircraft could potentially contribute less to global warming by avoiding places where local weather conditions make them more likely to be produced.

One of the aims of the OPAL contrail survey was to test whether the quality of data submitted by citizen scientists was good enough to support further research in this area.

Met Office experts and scientists from Lancaster University compared OPAL results with data from trained observers and numerical climate models. They concluded that the quality of citizen science observations in this particular exercise were "relatively high".


Blowing bubbles to measure wind speed

Another OPAL Climate Survey exercise asked participants to determine wind direction and speed, using the movement of clouds at high levels in the atmosphere, and soap bubbles at ground level, as a guide.

The data collected by OPAL citizen scientists was again compared against official Met Office data.

Wind direction estimates from both the cloud and bubble experiments were found to match, but did not correspond well to Met Office data. It's thought that partcipants may have confused the convention for describing where the wind was coming from with where it was going to when recording their results. Better explanation and clearer guidance was recommended in future.

The OPAL wind data was also used to compare wind speeds in urban environments. In urban areas there may be complex micro-climates which affect individuals' experience of the weather.

The standard height for official meteorological measurements of wind speed is 10m. At ground level results from citizen scientists confirmed the mathematical relationship between the two: for dense urban environments the wind speed at person height is generally 0.2 to 0.3 times the wind speed at 10m.

In future the information gained from this part of the OPAL Climate Survey may help to improve localised weather forecasting for urban areas.

Thermal comfort

Cold woman in warm clothes

How people actually experience the weather - especially how hot or cold they feel - may depend on a variety of factors. 

We surveyed participants to discover their perception (how hot or cold does it feel to you?), their preference (would you prefer it to be ...), and their response to the weather (clothing).

The results of the OPAL Climate Survey, and other studies, help experts to better understand how sensitive people are to climate, and how adaptable we might be to a changing climate.


So what is 'hot' and what is 'cold'? To the nearest whole degree, we found that OPAL respondents perceive the following thresholds:

Cold Neutral Hot
6 °C 15 °C 26 °C

When compared to studies in other European locations however, it becomes obvious that people's perception of thermal comfort (how 'hot' or 'cold' they feel) is influenced by local expectations.

  ‘Neutral Temperature’ Climatological average daytime maximum temperature
Athens, Greece 23 22
Milan, Italy 18 17
OPAL Survey, UK 15 14
Cambridge and Sheffield, UK 15 14
Fribourg, Switzerland 14 13
Kassel, Germany 18 12


The preferred outdoor temperature range for the UK was found to be in the range 19 °C to 22 °C.


The OPAL Climate Survey also asked particpants to tell us what clothes they were wearing outside, and at what temperature, when conducting the survey. These were the results:

Category Temperature range within which this category is most likely
(a) Summer wear Above 22 °C
(b) Warmer weather wear 19 °C to 21 °C
(c) Everyday wear 8 °C to 18 °C
(d) Everyday outdoor wear 5 °C to 7 °C
(e) Cooler weather wear 0 °C to 4 °C
(f) Winter wear Below 0 °C


As the OPAL survey data has shown, different meteorological factors such as sunshine, wind chill and humidity all affect how warm or cold people feel. Temperature alone is not the most effective indicator.

People's thermal comfort is not only influenced by the weather, but also by their local climate and what they might expect.

This knowledge will help to predict how people may respond to future changes in climate, especially increases in average temperature and more frequent heatwaves.

Find out more

  • Further analysis of the OPAL Climate Survey data, including additional information about OPAL's urban weather station experiments in Hull and Manchester, can be found in the Met Office OPAL Climate Survey summary (PDF, 1.1MB).
  • Detailed analysis of the OPAL Climate Survey contrail data can be read in the following research article: Fowler, A., Whyatt, J.D., Davies, G. and Ellis, R., 2013. How Reliable are Citizen‐Derived Scientific Data? Assessing the Quality of Contrail Observations Made by the General Public. Transactions in GIS, 17(4), pp.488-506. DOI: 10.1111/tgis.12034
  • The OPAL Climate Survey is now closed, but you can still study climate using our OPAL climate resources.