Set: Part No: ST011693
CTO: Part No: ST011694
FDC: Part No: ST011695
Clouds are a major feature of Falkland Islands weather. Influenced by the predominantly westerly winds which arise on the South American Continent together with the effects of the Andes, cloud forms are varied and extensive. Clouds are further modified by the Island terrain to form “mountain modifications” which develop from the higher elevations, “Roll cloud” at low levels, particularly in northerly winds forming behind the Wickham Heights and Cumulonimbus which generally form in southerly winds.

In this four stamp issue three of the more common cloud forms to be seen in the Falkland Islands are depicted: Altocumulus on the 76p value, Altocumulus lenticularis on the £1.01 value and Cumulonimbus and Stratocumulus on the £1.22 value.

The 31p value shows a rare form of cloud called asperitas (latin for “roughness”). Cloud watchers have been reporting these oddly shaped clouds for several years and due to the efforts of the Cloud Appreciation Society over many years it is expected that this new cloud type will finally be getting official recognition. This year the World Meteorological Organization (WMO) proposed a definition for the clouds. “A formation made up of well-defined, wavelike structures in the underside of the cloud, more chaotic and with less horizontal organization than undulatus. It is characterised by localized waves in the cloud base, either smooth or dappled with smaller features, sometimes descending into sharp points, as if viewing a roughened sea surface from below. Varying levels of illumination and thickness of cloud can lead to dramatic visual effects”.

It is hoped that the WMO will include asperitas in its revised 2016 International Cloud Atlas making it the first new cloud type identified since 1951. The inclusion of this rare cloud in this issue from the Falkland Islands is therefore both significant and timely.

The issue also features Luke Howard, who became known as the “Namer of Clouds”, on the First Day Cover. He was born in London on the 28 November 1772, was educated at a Quaker school in Burford Oxfordshire and was then apprenticed to a retail chemist in Stockport. He became like his father a businessman developing a firm that manufactured pharmaceutical chemicals. His real interest was however in meteorology and he made a number of contributions to the subject.
The most significant of these was his 1802 paper entitled “On the modification of clouds”
('modification' meaning 'classification'). In this paper he proposed a number of cloud names which are still in use today. Howard introduced three basic cloud types some examples of which appear in this stamp issue.

• Cirrus (Latin for a curl of hair)
• Cumulus (meaning heap) a form depicted on the 76p value
• Stratus (meaning something spread)

He combined these names to form four more cloud types:

• Cirro-cumulus, which he described as “small well defined roundish masses, in close horizontal arrangement”
• Cirro-stratus
• Cumulostratus
• Cumulo-cirro-stratus or Nimbus which he called the rain cloud, a form of which is shown on the £1.22 value

He was elected a fellow of the Royal Society in 1821 and joined the British, (now Royal Meteorological Society) in 1850; a month after the society was founded. He died in London on the 21 March 1864.

With thanks for the support of:
Alistair Price, Mount Pleasant Met Office.
The Cloud Appreciation Society. 
The Royal Meteorological Society, the UK’s Learned and Professional Society for weather and climate.

Technical details:
Designer Ian J. Strange
Photography Georgina Strange and Ian J. Strange
Image of Luke Howard Royal Meteorological Society
Printer: BDT International Security Printing
Process: Lithography
Perforation: 14 per 2cms
Stamp size: 51.46 x 30mm
Sheet Layout: 10
Release date: 9 December, 2015
Production Co-ordination: Creative Direction (Worldwide) Ltd