Met Office Weather Station

June and July were sweltering! Unfortunately we weren’t recording weather data until the second half of July, but we are now an official Met Office weather observation station. We have been up and running for a couple of months and most teething problems have been sorted.

Originally we approached the Met Office to see if either they had any old equipment they could give or sell us, or they were interested in having an observation station here. As it turned out, there was a gap in their network – just here in Bewcastle! That meant they would provide and maintain all the equipment if we would commit to undertaking daily readings – which is precisely what we wanted.

Tony Eastham, Regional Network Manager for the Met Office, installed the site once he had selected the exact location and we had erected the fencing. We selected the climate variables we wanted to record, with one of the main criteria being simplicity – we wanted no electronic gadgets. The only thing you can know for sure about anything electronic or electrical is that it WILL break – one day. We wanted equipment that will keep going and going, through all weathers and in all conditions, for tens and tens of years. We also wanted to record soil temperatures for growing purposes.

The installed Met Office station. Visible is the Stevenson Screen, the raingauge, and the sunshine recorder

The installed Met Office station. Visible are the Stevenson Screen, the raingauge, and the sunshine recorder. Also the top of the 100cm soil thermometer cap is just the other side of the fence. The view is towards  East (the Orient).

So all our equipment is ‘low tech’, but precision. Mainly thermometers – we have 8 of them: one ‘dry bulb’ (air temperature), ‘wet bulb’ (measures humidity when compared with dry bulb), maximum and minimum reset every morning, grass minimum, and soil at 10cm, 30cm, and 100cm.

Inside the Stevenson Screen: dry bulb (left), wet bulb (right), maximum (horizontal upper) and minimum (horizontal lower) thermometers

Inside the Stevenson Screen: dry bulb (left), wet bulb (right), maximum (horizontal upper) and minimum (horizontal lower) thermometers. Grass minimum can be seen on the grass in the background, just above and to the right of the raingauge.

We also record rainfall (24 hr), barometric pressure (both weekly charts and precise instantaneous), and have privately installed four tensiometers, recording soil moisture tension (the suction that plant roots have to exert in order to extract capillary water from the soil) at 20cm, 40cm, 60cm and 100cm. These latter are not reported to the Met Office but are for our own records.

In addition, at the time of the observation (9am GMT), we record visibility, wind speed and direction, ground state, snow depth (if any), and current (or recently ceased) weather.

However, the pièce de résistance is the sunshine recorder. Ours is the only one north of Morcambe Bay (in England). In this extraordinary instrument, the solar system can be seen at work.

Sunshine Recorder with an inverted image of Greenholme.

Sunshine Recorder with an inverted image of Greenholme.

It operates in much the same way as a sundial, except that, instead of casting a shadow, the sun’s rays are concentrated through the glass globe and brought to a focal point on the frame behind. The frame is fitted with a strip of paper marked with the hours of the day, and, as the earth rotates on its axis, the focussed beam from the sun burns a trace in the paper. We change the strip each day and measure the total length of time the sun has been strong enough to cause a burn on the paper. In clear skies it burns completely through and we are left with almost two separate pieces! You can observe the burn trace on the above picture, and see it was taken was just before 2pm (1pm GMT, where the burn has currently reached; the ’12’ of midday is visible on the paper).

The instrument required careful setting up, as it has to be aligned perfectly with polar south in order to burn an even trace throughout the day.

Tony Eastham of the Met Office setting up the sunshine recorder.

Tony Eastham of the Met Office setting up the sunshine recorder.

It is fascinating to observe the progress of the earth’s tilt away from the sun, which at the moment, is observable as a millimetre shift upwards in the trace each day (when we have sun!).

Our observations are uploaded daily (usually) onto the Met Office’s Weather Observations Website (WOW). You can view graphs and data there for the last month at any time.

(The beginning of wisdom is the most sincere desire for instruction, and concern for instruction is love of her. Wisdom of Solomon 6:17)

Greenholme - an experiment in permaculture

So what do you think?