Two more days on Arran with some glorious early autumn sunshine in addition to our typical mix of cloudy and shower weather. A sequence of our 12Z radiosonde soundings from Tuesday to today (incorporated intothe Met Office observation processing suite) shows this fluctuating picture of air masses which we have observed
On Tuesday, Arran was dominated by the cold front which made our walk up Goat Fell a little taxing, two cloud layers can be seen, with frontal cloud up to around 700hPa and higher level cloud (which we observed at the end of the walk aloft. You can also see the change in wind direction as the sonde moves through the front into the drier, cloud free air aloft.
On Wednesday, a much drier profile in general, with some remnants of the features above, but little in the way of cloud or change of wind direction as the sonde ascended. In general, winds were from the south and significantly weaker than on the previous day. Loch ranza was located between two weak frontal structures associated with the dissipating system that brought us rain on Tuesday.
On Thursday, the sonde ascended through some thin stratiform clouds, giving drizzle at times during the morning associated with the now almost completely dissipated system and its occluded front.
On Wednesday the group successfully launched an ozonesonde which made measurements all the way to 32km recording some interesting structure in the chemical profile of both the troposphere and stratosphere. More tomorrow including some student analysis. In the meantime, here are some photos of the launch led by the one and only Alan Gaddian from NCAS. Note the large payload and balloon needed for the ozonesonde (about five times larger than the standard).