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The Mull of Kintyre Lighthouse and 'The Dug's Lugs' looking westwards to The Atlantic
| Kintyre and Gigha, but not Rathlin Island, lie in The Gulf Stream, the prevailing winds are from the south-west. Kintyre’s weather is very localised and one often only needs to go but yards, rather than miles, to escape the showers. When rain comes in from The Atlantic and sweeps across the south end of Machrihanish Bay towards Campbeltown, one will often find parallel rain bands sweeping across from Crinan to Lochgilphead, from West to East Loch Tarbert and from Gigha, across Kintyre’s spine, to Carradale and across Arran to Brodick and Lamlash. It can be raining in Tayinloan and Pirnmill but totally dry in Carradale and Brodick ! It can be dry and warm at Bellochantuy and yet wet and cold in Glenbarr, just a couple of miles away. So now, what happens when a typical depression crosses Kintyre and The Clyde ? Facing into a moderate West wind, the ‘low’ will lie about NNW and the depression will be moving from SW to NE. There may be some low cumulus cloud on the horizon but, ahead of it and high up in the sky, one will see streaky cirrus cloud and ‘mares’ tails’ precede the warm front. This is closely followed by a thin, almost transparent, veil of cirrostratus cloud which may throw a halo round the sun (or moon) - the open section of the halo indicating the direction of the incoming weather. The barometer will begin to fall and the wind will back - go anti-clockwise - to the South. Dense grey and thickening stratus clouds will bring increasing amounts of rain and a further fall in the barometer. The wind will increase in strength and again back further south, or south-east. As the warm front passes, the barometer will steady and the wind will veer - go clockwise - to the SW as the rain eases. The cold front now causes the barometer to fall again slightly and more rain comes as the winds backs again, towards the south or south-east. At the front itself, the wind veers sharply NW or N and, as the clouds now begin to break up, the barometer starts to rise. Squally showers may continue for a while but the barometer will now continue to rise and the grey cumulus clouds begin to separate indicating that ‘the low’ has taken its course. A depression could be 1,000 miles across, be slow moving and take a week or more to pass ! Around ‘lows’, winds, angled about 20 or 30 degrees inwards, circulate anti-clockwise in The Northern Hemisphere - clockwise in The Southern Hemisphere. The centre of a ‘low’ lies about 60 degrees to the right of the individual’s direct line of sight when facing into the wind in The Northern Hemisphere - to the left in The Southern Hemisphere. Around ‘highs’, winds, angled outwards, circulate clockwise about their centres in The Northern Hemisphere - anti-clockwise in The Southern Hemisphere. The centre of a ‘high’ will be to the left of the individual when facing into the wind in The Northern Hemisphere - to the right in The Southern Hemisphere. Cold and Occluded (Mixed) Fronts move forward faster than Warm Fronts. Wind Strengths may be 30% less where isobars are curved tightly round a ‘low’ but may be 50% greater if the isobars are curved round a ‘high’. Isobars are drawn at 4 mb (millibar) intervals, from the centres of ‘lows’ and ‘highs’. Two simple wind / speed conversions are easily remembered - Force 5 = 25mph and 60mph = 100kph. Wind Speeds may be assessed quickly by looking at the distance between isobars. Thus the following comparison of distances etc.. Force 2 (About 4- 6 knots) From N. to S. England 360 miles
Force 3 (About 7-10 knots) From N. to S. Ireland 270 miles
Force 4 (About 11-16 knots) From N. to S. Wales 150 miles
Force 5 (About 17-21 knots) Blackpool to Newcastle 110 miles
Force 6 (About 22-27 knots) Bristol to Isle of Wight 85 miles
Force 7 (About 28-33 knots) Solway Firth to Newcastle 70 miles
Force 8 (About 34-40 knots) Dover to Calais/Boulogne 30 miles Indications of approaching changes of weather and changes in the directions and forces of winds are shown less by the height of the barometer than by its rate of falling or rising. Weather forecasts are based on the average rates of change over 3-hourly periods. Gale Warnings are reported as Imminent (in less than 6 hours), Soon (in the next 6 to 12 hours) and Later (in the next 12 to 24 hours). Weather Systems being reported as moving Slowly (between 1 and 15 knots per hour), Steadily (15-20 knots), Rather Quickly (25-35 knots), Rapidly (35-45 knots) and Very Rapidly (over 45 knots per hour). | 
