ByAlan Rogers
WE have learned that generals and dictators do not always learn much from past history as Hitler showed in his disastrous attempted invasion of Russia. He paid no heed to Napoleon’s even greater campaign and aborted push towards Moscow, in winter too, a century before. However, much of modern meteorology has developed from war time experiences and necessity.
It was the Norwegians, Vilhelm Bjerknes and son Jacob, who can be credited as the founders of modern weather forecasting. In 1912, Vilhelm as professor of Meteorology — a new science then — at Leipzig University was persuaded by the Norwegian Arctic explorer Nansen to become professor of Geophysical Sciences at the newly founded Bergen University and to return to Norway.
Later in World War I (WWI), when weather ships were withdrawn from the North Atlantic Ocean because of u-boat activities, father and son Bjerknes identified temperate and polar air masses that converged to create a cyclone or depression or typhoon (low pressure areas), which have their own cycle from birth to decay. Such were the words used on the Western Front and the Eastern Front in WWI battles. The airmass fronts meet to battle for the weather at ground level. This model of the development of a cyclone from its inauguration to its death holds true in the 21st century and is easily observed now from meteorological satellite images.
During the blitzkrieg of major British cities in World War II RAF (Royal Air Force) fighters could not get into the air to intercept German bombers and were grounded by thick fog.
We know here in Kuching that very early morning fog becomes ‘burnt off’ by the sun by 9am. So to allow the fighters to take off, meteorologists devised petrol burners placed at intervals along runways. The heat produced at ground level caused the fog to clear and created a clear channel for take off. Having done their job, the pilots could not land as the fog banks again closed in, hence a number of pilots had to ditch in the English Channel — there to be rescued!
We know that fog like a cloud consists of millions of minute suspended water droplets held aloft by rising air. It was the research in Massachusetts in the mid- 1940s by Dr Irving Langmuir and Vincent Shaefer who discovered that by spraying or seeding clouds with pellets of solid carbon dioxide — dry ice — the water droplets were ‘fooled’ into condensing on the pellets and artificially created snow fell.
Within our clouds are natural condensation nuclei — particles of soot, volcanic dust, soil and salt. In temperate latitudes when cooled at a sub zero temperature the water droplets condense on the these nuclei and the latter grow in form until they become too heavy to be suspended and thus fall out as snow or rain.
It is recorded that the ancient Chinese and Leonardo de Vinci ‘pierced’ clouds, thinking that they were ‘bags of water’, by using fireworks. Purely by chance this sometimes worked for, unwittingly to them, the fireworks contained silver iodide acting like dry ice! It all depended on the temperatures near the cloud base which actually needed to be at -5 degrees Celsius for this to happen.
In tropical/equatorial latitudes there are few if any natural ice condensation nuclei amongst the water droplets in our clouds. In the 1950s in the semi- desert areas of Pakistan during periods of drought the farmers prayed to Lord for rain. Imans told them to go out and plough their salt encrusted fields. The farmers did just that and unwittingly released millions of salt particles rising in the heat to passing clouds. The salt particles acting as condensation nuclei absorbed the water droplets and through turbulence in the clouds the nuclei banged together and coalesced ... too heavy now to be suspended by up draughts and rain fell.
Take the same principle here in Sarawak. On the eve of 2006’s Independence Day Celebration, after a prolonged period of haze and before the King and the Prime Minister would witness the National Parade held here in Kuching, a Hercules aircraft of the Royal Malaysian Air Force took off at about 7.45pm from Kuching and seeded the clouds above with a fine spray of a saline solution.
Within three hours there was a tremendous downpour lasting another few hours. The pollutants in the air were washed out of the sky and the next morning witnessed a glorious parade for the thousands present. The RMAF (Royal Malaysian Air Force) is credited, with some of the most successful cloud seeding operations in the world, a high accolade indeed.
Norwegian Tor Bergeron and German Walthur Findeison together proposed the droplet coalescence theory in the late 1930s when war sadly intervened.
The 1920s saw a Japanese Professor Ooishi tracking high altitude balloon movements near Mt Fuji. The results of his findings were written in Japanese and later in Esperanto. Thus his findings were not understood yet he observed westerly tail winds at up to 240km per hour.
Why does an MAS or AirAsia flights take an hour less from London to Kuala Lumpur and an hour longer flying in the opposite direction? A flight from west to east saves the airline time and thus fuel ... sadly airfares do not reflect this. This is all because of jet streams first accurately recorded by Jerome Namias who investigated the comments of the B52 bomber pilot who dropped the first atomic bomb on Hiroshima for he noted that flying from west to east his aircraft was moving faster than its air speed indicator could record. In 1945, Carl G Rossby, a German, coined the word Jet Stream. To visualise the jet stream think of a modern gymnast in the Olympic Games with a ribbon in her hand which she thrashes through the air in undulations and meanderings. Observe the path of the ribbon as it twists and twirls.
Jet streams have high speeds and are tubular in shape and meander around our planet as west to east flowing air currents at altitudes of 10,000 to 15,000 metres. These tubes of fast flowing air are 2,000 to 4,000 metres wide thousands of metres long. There are between two to three jet streams in each hemisphere and they lie over areas at much lower altitude of great temperature contrasts between, as in the northern hemisphere, cold air masses to the north and warm air masses to the south. The Polar Jet lies roughly at 40 to 60 degrees north of the Equator and is responsible for the rapidly moving cyclones hitting Europe and the west coasts of North America in the winter months. In the summer months this jet weakens providing anticyclonic patterns hence higher temperatures.
The westerly blowing Subtropical Jet lies between 30 degrees north and south of the Equator and is at its strongest over India. Undoubtedly this is one ofthe most powerful wind systems on earth and surprisingly does not affect the underlying weather as much as the Polar Jet. Add to this the third jet stream at about 9,100 metres high, which affects us and our monsoonal wind patterns seen as the Tropical Easterly Summer Jet in October to April and the Tropical Westerly Jet in May to September when it is at its strongest.
All long haul pilots receive meteorological briefings on the positions of the jet streams on their flight paths long before they appear with the rest of the flight crew whilst you sit patiently in the boarding gate lounge. Watch the airspeeds on the video screen on your next flight and observe how head or tail winds speeds can affect the time of your arrival.
The recent volcanic eruption in Iceland that last exploded in 1825 and began again on March 20, 2010 reaching an ash plume climax on April 14 highlighted the vulnerability of mankind to nature. Theplume over Europe was driven south-eastwards from Iceland by the Polar Front Jet Stream. Whilst costing airlines some US$400 million a day and boosting the hotel trade in Southeast Asia that is a small price to pay for our safety!
Wars have brought undue suffering and devastation to mankind yet we should be eternally grateful for the ensuing medical and meteorological advancements caused by war. More of our prospective university applicants should be encouraged to read Meteorology or Atmospheric Physics to later join Meteorological Services at home and abroad for there is much above our heads still to be explained in a relatively recently discovered science.
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