About Erick Brenstrum

Erick is a Severe Weather Forecaster at MetService and is the author of 'The New Zealand Weather Book'.

The Weather at Passchendaele

We remember our war dead on Anzac Day, 25 April, the anniversary of the landings at Gallipoli in World War I. But our heaviest losses in that war occurred on the Western Front.

Our worst day was 12 October 1917 – the First Battle of Passchendaele. New Zealand lost 1,000 soldiers in two hours because the high command ignored the effect of heavy rain on the battlefield.

The Ypres Salient, in Belgium, where the campaign took place was low lying. Prior to the war the water table was 35 centimetres below the surface. The weather that year had been poor and from July onwards was the wettest for 75 years. Millions of artillery shells fired over the previous three years had obliterated the canals and small creeks that drained the area, turning the ground into a quagmire. Some shell holes were so deep and the mud so viscous that men drowned in them when seeking shelter.

Stretcher bearers, Passchendaele, August 1917

Stretcher bearers, Passchendaele, August 1917

Eight days before Passchendaele, the New Zealand Division took part in the battle of Broodseinde. By this stage of the war, the British had evolved artillery tactics that delivered some success. The attacking soldiers walked forward 50 yards behind a creeping artillery barrage, giving the German soldiers little time to recover from the shelling before our troops were on top of them. Heavy artillery shells cut the barbed wire while those German pillboxes and artillery batteries that had been observed before the battle were specifically targeted.

The New Zealand division achieved all its goals, advancing 1900 yards through knee deep mud. This modest advance was deliberate so that the inevitable German counter attacks were well within the range of British artillery and easily halted.

The New Zealand division suffered 25 per cent casualties, including 330 dead.

Intoxicated with such success, Field Marshall Douglas Haig, the general in overall command, was keen to push on as soon as possible. He was suffering from the delusion that the Germans were exhausted and a great breakthrough was imminent, through which his cavalry divisions would pour to end the war with one blow.

Before the attack could be renewed the artillery had to be moved forward over the captured ground. But the rain continued, making the ground all but impassable.

Soldiers with a gun at Passchendaele

Soldiers with a gun at Passchendaele

The mud was too deep to move the heavy guns up and many of the lighter guns bogged down. Shells for the guns were taken up by pack animal. One donkey, carrying two 18-pound shells slipped off the wooden duckboards and sank without trace into a flooded shell hole. Only a fraction of the necessary ammunition reached the guns. The mud and lack of time also prevented solid platforms being built for the guns that were in place.

Soldiers moving up during the night took four hours to struggle a mile through the mud, which was waist deep in places. Some never reached their start lines on time.

When the artillery barrage began it was so feeble that some soldiers could not distinguish it from the sporadic German shelling. Worse, when some of the British guns fired, the recoil shifted their alignments so that their next shells fell short and onto New Zealand troops.

The lack of heavy artillery left the 50-yard barbed wire entanglements uncut and the German’s concrete pillboxes undamaged. When the New Zealand soldiers went over the top they were slaughtered. Some companies suffered 85 per cent casualties and none of their objectives were reached. Stretcher-bearers struggling through the mire took hours to get wounded men to aid stations, sliding stretchers across the surface of the mud in places, while they struggled not to sink and drown.

Writing in Massacre at Passchendaele, New Zealand military historian Glyn Harper, believes the attack should never have been launched, blaming Haig and the generals below him for not listening to the junior officers who had warned of the terrible conditions beforehand. Other historians also blame Prime Minister Lloyd George and the War Cabinet who had allowed the Ypres campaign to proceed on the understanding that they would intervene to stop the fighting if it threatened to turn into a deadly debacle like the battle of the Somme the previous year. They failed to do so.

Ironically, over 500 years earlier, not far behind the frontline was the field of Agincourt, where heavy rain had given England one of its greatest military victories. A large French Army confronted Henry V on 25 October 1415. Most of Henry’s soldiers were archers. The French had six times as many men-at-arms and were confident of victory. However, they were badly led.

Their king, suffering temporary insanity, was absent. The French nobles, riven by bitter rivalries, all wanted to be in the front rank to capture the English king.

The field sloped uphill from the French positions and had been recently ploughed. Heavy rain overnight made footing treacherous – something the French leaders seemed to discount but Henry was aware of as his scouts had walked the field in the night.

After a three hour standoff, Henry took the initiative and advanced to within bowshot. On firm ground the French cavalry could have closed the gap in twenty seconds, making such an advance by lightly armed archers suicidal. When they did charge, the cavalry was slowed by the mud.

Their generation had not experienced massed English archery until that day. Shooting an arrow every five seconds, Henry’s 7000 archers could fire 80,000 arrows in a minute. The French cavalry was decimated. Those French soldiers protected by heavy plate armour sank knee-deep in mud churned up by the horses. Those who stumbled were trampled by those behind. A generation of French nobility died and Henry had one hand on the French crown.

If any good came out of Passchendaele, it was that the young officers who went on to become leaders in the Second World War had a stronger appreciation of the weather’s importance. The invasion of France, for example, scheduled for 5 June 1944, was put on hold for 24 hours because of a forecast of gales and rain. The forecast was correct, and catastrophe was averted.


Referenced texts:

  • Massacre at Passchendaele Glyn Harper
  • Passchendaele: The Sacrificial Ground Nigel Steel and Peter Hart
  • Passchendaele: The Untold Story Robin Prior and Trevor Wilson
  • Agincourt Juliet Barker
  • 1415 Henry V’s Year of Glory Ian Mortimer

This article was originally published in New Zealand Geographic March 2013. Stretcher-bearer image by John Warwick Brooke [Public domain], via Wikimedia Commons; artillery image courtesy of National Army Museum, New Zealand.

Hiding in the Rain

Man Alone by John Mulgan

In John Mulgan’s novel Man Alone stormy weather plays a crucial role hiding the hero, Johnson, when he is on the run after accidently killing a man on an isolated farm near Ohakune. Fleeing through the night on horseback, Johnson takes a track up Mount Ruapehu as a southeast storm is building.  He is aiming to hide in the wilderness of the Kaimanawa Ranges but cannot reach them before daybreak. After a few hours sleep in a hut near the bush line, he walks around the side of Ruapehu cloaked by rain and mist then drops down a ridge into the tussock country of the Rangipo desert.

But the weather that hides him from pursuit also threatens to kill him with cold. On his first night in the open, he digs a shallow trench into the pumice for partial shelter from the gale. The next day, the wind reaches its peak, becoming so strong it forces Johnson to his knees, blasts him with sand and disorients him. It’s moaning “more mournful and frightening than anything human he had known.”

The wind and the rain last the three days it takes Johnson to cross the open country of the central plateau and reach the safety of the Kaimanawa Ranges. He is ill by this time, but recovers in the forest, wintering over in a cave, before emerging on the Hawkes Bay side of the ranges in spring. Eventually Johnson escapes New Zealand by ship and ends up fighting with the International Brigade against Franco’s fascists in the Spanish Civil War.

Weather is often used to add drama to literature. Examples abound from the storms in Emily Bronte’s Wuthering Heights, to Shakespeare’s King Lear raging on the heath or the deadly effects of winter in Tolstoy’s War and Peace.

Mulgan was influenced by Hemingway whose famous novel, Farewell to Arms, has two moments when bad weather aids the hero, Frederic Henry, an American serving in the medical core of the Italian Army during the First World War.

In the chaotic retreat in the rain after a major defeat the remnants of the army crosses the flooded river Tagliamento. As the crushed mass of soldiers reaches the far side, military police single out officers or suspected enemy agents and execute them for causing the defeat. Doubly suspicious as an officer who speaks Italian with a foreign accent, Henry is seized but breaks free and dives into the river before he can be shot. A few days later, Henry avoids imminent arrest by civilian police, fleeing in the night by rowing down Lake Maggiore to Switzerland, hiding from border patrols in patches of mist and rain.

As a scholar of Latin and Greek, Mulgan was also likely to have been aware of stories of bad weather being used to advantage in ancient warfare. For example, during the Peloponnesian War between Athens and Sparta in the fifth century B.C. the Athenian general Alcibiades risked stormy seas to sail a large fleet undetected through heavy rain at night to close on Spartan positions at Cyzicus. The next morning, Alcibiades sailed forty ships towards the Spartans. Thinking this was all the force at his disposal, the Spartans launched their fleet and pursued Alcibiades as he retreated out to sea. This allowed the bulk of the Athenian fleet that was concealed behind a promontory, to sail behind the Spartans and cut them off from their base. The ensuing battle was a great victory for the Athenians, although it failed to determine the outcome of the war.

An interesting example of author as hero occurs when Julius Caesar was fighting in Gaul in the first century B.C. At the end of each year’s campaign Caesar wrote a history of the fighting and had it circulated in Rome. He could not stray too far from the facts as others in his army were also writing home, but Caesar’s version painted his actions in the best possible light in order to wrong foot his political opponents in Rome. In the siege of the fortified town of Bourges, Caesar writes that he decided to take advantage of a heavy rainstorm to launch his successful assault when the defenders were off guard.

In this story Caesar was echoing incidents from Homers Iliad – a work well known to educated Romans – where the gods used weather to intervene in the fighting between the Achaeans and the Trojans, causing a mist to descend over a warrior whom they sought to protect when the fight went against him.

A god wielding the weather as a weapon also decides the outcome of a crucial combat in the Sumerian Epic of Gilgamesh. The oldest story we know, Gilgamesh was written in cuneiform inscribed on clay tablets more than four thousand years ago and progressively unearthed in fragments by archaeologists over the last two centuries.  In order to fetch timber to repair the temples of his city of Uruk, as well as to gain the immortality of fame and glory, Gilgamesh undertakes a long journey to the mountains where cedar grows. The forest is guarded by the ogre Humbaba, who is protected by deadly auras – “his speech is fire his breath is death.” Gilgamesh triumphs because of the intervention of the sun god Shamash, who unleashes the thirteen storm winds to blind Humbaba.

Mesopotamian sun god Shamash

Mulgan himself went to war, fighting first in the desert at El Alamein and later behind German lines in Greece. His knowledge of the ancient Greek language enabled him to become fluent in Modern Greek so that he earned the reputation as the most effective liaison officer with the Greek Andartes, leading them in numerous attacks on the Germans defending the railway. These were carried out under cover of darkness but, as far as we know, bad weather was not used for deception, although Mulgan did travel cross country in daytime, shielded by rainstorms.

With its dangers and opportunities, the weather has been with us since the beginning and we have been hiding in the rain off and on for thousands of years.

Napoleon’s Winter

What would New Zealand’s history be like without the First and Second World Wars? Blame the terrible Russian winter and Napoleon’s folly according to historian Adam Zamoyski in his riveting book 1812 Napoleon’s Fatal March on Moscow. The losses suffered in the invasion, particularly to his cavalry, ensured Napoleon’s downfall the following summer. That led to an aggressive Germany unified under a militaristic Prussia while in Russia, the Tsar came to believe he was God’s instrument on Earth. Growing more conservative as he aged, his repression of the generation who defeated Napoleon sowed the seeds of the Russian Revolution.

Napoleon’s army began retreating from Moscow on 19 October in fine weather. Three days later, rain turned the road to mud making travel difficult. On November 6, the first snow fell and soldiers froze to death overnight when their campfires burnt out. Once the snow compacted, it became rock hard and slippery, causing men and horses to fall. Carriages and guns had to be controlled on slopes using ropes held by dozens of soldiers. When they slipped, the guns crashed into vehicles ahead of them, creating chaos.

When horses fell, they often broke their legs. In the space of a few days the army lost tens of thousands of horses to cold and accident. The Polish cavalry came through best as they had shod their horses in Moscow with shoes like crampons. Among the French, only the horses of the Imperial household had followed their example, on the orders of General Caulaincourt, a former ambassador to Russia who had experienced their winters before.

A few of the French acquired small Cossack horses that had broad hooves and a low centre of gravity. These horses also knew how to slide down slopes by sitting down on their hindquarters still with the rider on their back.

Most of the army slept in the open, but the few huts still left standing often became death traps. So many men crowded inside to shelter that some suffocated in the crush. Huts often caught fire, either from their wooden stove overheating or campfires set too close outside the building by soldiers ripping timber off the hut walls.

On the night on November 12 the temperature dropped to minus 24 C and frostbite became widespread among the troops. Not recognising the symptoms or knowing the treatment, many men lost noses, fingers and toes. With such a hard frost, there was no liquid water readily available, so men and horses suffered badly from dehydration.

The churned up road surface froze into sharp ridges that lacerated shoes and feet cutting some to the bone. Stragglers that fell behind were captured by Cossacks, stripped naked and left to die, or sold to peasants who tortured them to death in revenge for their own sufferings.

Men ate horsemeat flavoured with gunpowder for the salt. Horses that died became rock hard in minutes so had to be cut up while still alive – including horses still walking. When the owner looked away, a steak could be slicked from the numbed flank of a horse. The cold froze the blood and the horse would survive a few days longer.

But it was the river crossings that posed the greatest danger. As the traffic bottlenecked, people were knocked over in the crush, trampled underfoot and killed. Russian artillery, drawn on sleds, sometimes caught up and shelled the crowd. The bridge over the Berezina had been burnt so 400 pontooners built two new ones working up to their necks for 15 minutes at a time in freezing water as ice floes washed past. Only eight of these men survived the retreat.

crossing the Berezina

Crossing the Berezina (Source: Wikipedia)

A two day blizzard starting on November 29 was remembered by survivors as the worst time. Some shot themselves. Those whose shoes had disintegrated got such bad frostbite that skin and muscle peeled away from the bones of their feet. Soldiers who feel down had their boots pulled off before they died. Men murdered for fur coats and there were incidents of cannibalism.

When the blizzard passed, clear skies allowed the temperature to plunge. It fell to minus 37 C on December 6. At this temperature liquid water cannot exist in the air and water molecules combine to form ice crystals that sparkle in the clear sky – a phenomenon meteorologists call “diamond dust”.  Men’s breath was as thick as smoke and condensation formed icicles in hair eyelashes and beards which grew thick enough to obstruct vision and breathing.  Eyelashes froze together and had to be pressed between fingers so eyes could be opened. Many got snow blindness, causing tears, which froze.

It was now so cold that men died walking. Blood suddenly streaming from mouth and nose and sometimes eyes and ears, they would stagger a few steps like drunkards before falling. Many now had dementia, some so disorientated that they would walk into fires in bare feet and lie down. One gunner froze to death standing behind his cannon, hand on the breech and facing back towards Russia.

Two fresh divisions were deployed in front of the town of Vilna to stop the Russian advance, but, not hardened to the cold, almost all froze to death over two nights. Nor were the Russians spared the suffering. Of the 97,000 who pursued the retreating French, only 27,000 reached Vilna.

The Russian general Denis Davidov remembered colder winters in previous years, but not with large starving armies wandering around in the open. In all, counting civilians and soldiers on both sides, around a million people died because of Napoleon’s invasion of Russia. In the opinion of general Caulaincourt, had Napoleon left Moscow two weeks earlier it is likely he would have extricated most of his army intact and continued to control much of Europe. But the warm start to autumn deceived Napoleon as he waited in vain for the Tsar to negotiate.

1812 was not the first time an invading army came to grief in a Russian winter. In 1709 the Swedish king Charles XII lost a third of his forces in winter before defeat at Poltava by Peter the Great.

Nor was it the last. Two hard winters during the Second World War contributed to the German Army’s ultimate defeat. A witness later remembered Hitler fuming in December 1941 “These damned meteorologists, also they are talking about Napoleon.”

First Published: New Zealand Geographic July-August 2010

Weather Place Names

There is a lot of weather tied up in New Zealand place names. The screaming northwest gales of Canterbury are celebrated with names like Windwhistle, near the Rakaia Gorge, Mount Blowhard, near Oxford, and Nervous Knob, near Castle Hill, where gusts of 240 km per hour have been measured.

Fine weather gets a mention with Sunnynook and Sunnyvale, both near Auckland. We have a Misty Peak and a Cloudy Bay and rainbows are well represented, being used to name an island, a mountain, a lake and a pass. Rain itself is harder to come by but can sometimes be found in the story that gave rise to a name.

Photo courtesy of New Zealand Geographic

Fittingly, several of these occur in rainy Fiordland. Monkey Creek, for example, commemorates a downpour that flooded a creek and washed away a surveyor’s dog, called Monkey, who fortunately made it back to camp the next day. Also in Fiordland Stick-up Creek was named by Martin’s Bay settlers, who were held up by a flood, while Mount Soaker speaks for itself.

In May 1773 James Cook laconically named Wet Jacket Arm in Dusky Sound after a storm forced an exploring party to stay out overnight. In Lieutenant Pickersgill’s words “On the 7th I went with the Pinnance to explore a Sound, expecting to get back on the same Night but was disappointed for it came on a very violent storm of Snow Hail and Thunder with a meer Hurrican of wind which confined us in a little Cove, and what was worse we had nothing to eat but a few Mussels which we gathered from the Rocks and nothing to drink but spring water; in this situation we were kept for 36 hours, quite wet and the woods so wet we could not get a bit of fire to burn and being entirely exposed to the inclemency of the weather.”

The naturalist, Forster, was rattled by the ferocity of the storm “ it seemed as if all nature was hastening to a general catastrophe … our hearts sank with apprehension lest the ship might be destroyed by the tempest and its aetherial fires, and ourselves left to perish in an unfrequented part of the world.”

There is also a storm hidden behind Cook’s naming of Hawke’s Bay. First Lord of the Admiralty, Edward Hawke, rose to fame as the only naval commander in the age of sail to initiate a battle in a full gale.  In November 1759, Hawke ordered his fleet to pursue the French as they retreated into Quiberon Bay seeking a safe harbour. The English ships crammed on so much sail in the chase that some of them sustained damage. The seas were so large that water entered some ships through their gun-ports. One of the French ships capsized and sank in a squall when this happened while the English ships managed to right themselves and shed the water.

Caught off balance by the audacity of Hawke’s attack the French Admiral never regained the initiative. The result was a crushing victory, which ended all hope the French had of transporting their large army of invasion to England. Had the English not won the war, some historians speculate that the USA might be speaking French today and not English.

There are also a host of Maori weather stories in New Zealand place names, as a trawl through A.W. Reed’s excellent Place Names of New Zealand will show. Kaihau-o-Kupe near Wanganui remembers a time when Kupe was held up by persistent westerly gales and rough water and had to “eat the wind” as he had no food with him.

Tongaporutu near Waitara translates as “driving into the south wind at night” and was given by the explorer Whatonga when he was sailing down the west coast searching for his grandfather Toi.

Upokopoito near Wanganui translates as “calabash heads”. The story goes that a red-headed chief heard that fishermen had mockingly compared him to a red gurnard. A tohunga obliged the chief by calling up a gale that swamped the fishermen, whose heads bobbing in the water looked like calabashes.

The Maori name for Wellington’s Mount Victoria is Tangitekeo, literally “the sound of the peak” as this was where the taniwha Whaitaitai screamed, a sound like the howling of the wind.

As befits a country astride the roaring forties, many names reference the wind. The Maori name for Solander Island in Fovueax Strait is Hautere, or flying wind while elsewhere there is a Hauiti, or little breeze, a Haunui, big wind or frequent wind and a Haumoana or sea wind.

Quite a few names commemorate misfortune, such as the numerous coastal features named after ships wrecked in storms: Benvenue Cliffs near Timaru; Buffalo Beach in the Coromandel and Union Bay near Auckland.

Mount Paske is named after a surveyor who lost his life in a snowstorm while Canterbury’s Jason’s Creek remembers a man who got severe frostbite cutting firewood and had both legs amputated at the knees.

Graveyard Gulley near Alexandra is named for two travellers killed in a snowstorm while Deadmans Terrace, on the Shotover River, is where eleven gold prospectors were killed in a horrendous flood.

A touch of humour is evident in The Gluepot, which occurs in Otago and Westland for places where carts were regularly bogged down after rains turned to roads to quagmires.

Among the many names bestowed during the voyage of the survey ship HMS Acheron in the 1840s was Blanket Bay in Fiordland, after a blanket of fog encountered there. Acheron made its way into several place names and was originally the name of a river in the Greek Underworld. Interestingly, some scholars believe the syllable ach goes back thousands of years further and is an Indo-european root word associated with streams that gave rise to the latin word aqua.

Perhaps the most delightful discovery in Reed’s book concerns a place on Banks Peninsula called Snefellness by a Danish whaling captain in 1840. It means a promontory surrounded by a snowfield and is now mispronounced as Snufflenose.

Benjamin Franklin – Electrical Ambassador

(First published in new Zealand Geographic 96, March-April 2009)

We think of Benjamin Franklin as American, but for the first seventy odd years of his life he thought of himself as British. In turn, the British thought him one of theirs and embraced Franklin’s ideas and inventions as British discoveries.

For example, on his first voyage to New Zealand Captain Cook carried one of Franklin’s lightning conductors. Caught in a thunderstorm in Batavia (Jakarta), the Endeavour was struck by lightning but unharmed while a Dutch ship nearby had its mainmast shattered.

On 18 May 1773, during his second voyage to New Zealand, Cook was sailing the Resolution towards Stephen’s Island when he met with six waterspouts. As the sky darkened with cloud threatening strong winds, he ordered all sails “clewed up” to lessen the risk of damage. Four waterspouts rose and spent themselves between the ship and the land, a fifth was out to sea, but the sixth passed about 50 metres away from the stern of the Resolution.

Cook was familiar with Franklin’s theories about waterspouts, in particular, Franklin’s speculation that a large gun fired into one would disrupt it. Franklin, on horseback and armed with two pistols, had once chased a whirlwind down a country road in Virginia but it got away over a fence before he could shoot it. Cook endeavoured to try the experiment and ordered a cannon loaded and aimed but the waterspout had moved out of range by the time the gun was ready.

Franklin’s work on electricity won him international renown. The experiments he proposed, in a paper published by The Royal Society, proved that lightning was a form of electricity. This had long been the subject of speculation. Newton, for example, had described a spark jumping between the tip of a needle and a piece of amber rubbed with silk “The flame putteth me in mind of sheet lightning on a small – how very small – scale.”

Representation of waterspout accompanying "Water-spouts and Whirlwinds" by Benjamin Franklin. Figure III represents the semimagic square Benjamin Franklin constructed in 1750 having magic constant 260.

Franklin proposed building a sentry box on a tall tower with a 10 metre iron rod connected to an electrical stand. A person holding a grounded wire by insulated handles could draw sparks from the iron rod to the wire when an approaching thunderstorm charged the rod.

While Franklin waited for a tall tower to be built in Philadelphia he hit upon the idea of flying a kite into a storm and drawing sparks from a key attached to the kite string. By the time he successfully carried this out in June 1752 his original experiment had twice been successfully conducted in France, although news of this had not yet reached America.

Franklin was the first to use the terms positive and negative to describe electric charge. He also came up with the concepts of batteries and capacitors and the distinction between insulators and conductors.

Aside from explaining the nature of lightning, Franklin made other contributions to meteorology. He explained the paradox that an easterly storm could affect Philadelphia before it reached Boston, even though Boston lay further east. The answer was that the storm was a large whirling vortex of wind that moved eastwards across the land.

He correctly deduced from summertime hail that there must be a high layer in the atmosphere where temperatures were always as cold as winter. He astutely blamed volcanic eruptions in Iceland for “dry fog” experienced throughout the northern hemisphere in 1784 that brought an extremely cold winter.

Franklin had time to indulge in scientific speculations, as well as enter politics, because he had been so successful as a printer he was able to retire at forty-two. Among his popular productions was Poor Richard’s Almanack which contained information on tides, moon cycles, weather, sundry advice and pithy sayings such as “A countryman between two lawyers is like a fish between two cats.”

Borrowing a trick from Jonathon Swift, Franklin predicted the death of a rival. When the due date arrived, he pronounced the man dead. When his rival claimed to be still alive, Franklin dismissed the protests as a cruel hoax perpetrated by others trying to make money from the dead man’s name.

Franklin’s weather forecasts a year ahead were also tongue in cheek – “Ignorant men wonder how we astrologers fortell the weather so exactly…Alas! ‘tis easy as pissing abed. For instance: the stargazer peeps at the heavens through a long glass; he sees perhaps Taurus, or the great bull, in a mighty chase, stamping on the floor of his house, swinging his tail about …Distance being considered, and time allowed for all this to come down, there you have wind and thunder.”

Franklin’s scientific work made him the most famous American in Britain and Europe. He was the first person outside Britain to receive the Royal Society’s Coply medal. Hailed by the German philosopher Immanuel Kant as the “modern Prometheus”, Franklin was elected a foreign associate of the French Acadamy of Sciences and received honory degrees from numerous universities.

In politics he played a vital role in the decades before the American Revolution. Once war broke out, he helped write the Declaration of Independence then was given the crucial task of handling the French alliance. Hailed as the “electrical ambassador” in France, the French statesman Turgot said of Franklin “He snatched lightning from heaven and the sceptre from tyrants.” One portrait showed Franklin enthroned in the sky surrounded by winged deities with a lightning bolt behind him. Louis XVI, although helping the American cause, had a Sevres chamber pot made with Franklin’s portrait inside as a gift for one of Franklin’s admirers.

By the time Britain was defeated and a treaty negotiated, Franklin was eighty. Sailing home, he found time to measure the depth of the Gulf Stream using a corked bottle on a thirty-five fathom line. The pressure at depth forced the cork into the bottle followed by deep water. Pulled back to the surface, the water temperature was 12 F colder than the surface, proving that the Gulf Stream was a relatively shallow layer of warm water.

Back on land, Franklin returned to politics and helped revise the Constitution, before dying aged 83, one of the most remarkable statesmen-scientists the world has seen.

Rugby Weather: Fog

Rugby and fog do not go well together. Fortunately, in the days when rugby was played in the afternoon, they did not meet up much, except for the occasional test in Scotland when the All Blacks disappeared into the “gloom” as they scampered in a late try.

However, the introduction of night-time rugby gave fog a chance to get on the field for some game time. Especially in the United Kingdom, where evening games sometimes have to be cancelled when fog turns up.

In New Zealand, fog showed us what it could do when it rolled into Christchurch an hour before the kickoff of the Super 14 final between the Hurricanes and the Crusaders on 27 May 2006.

As a television spectacle the event was seriously compromised. The cameras down at ground level sometimes got a reasonable view but those high up were mostly obscured. Nicknamed “gorillas in the mist” the contest was won 19-12 by the Crusaders.

The Hurricanes, who do not have much fog of their own as it is usually too windy in Wellington, also got to suck up some Hamilton fog at the end of the Super 14 semi-final against the Chiefs in May 2009, which they also lost. Situated on a river, with swamps nearby, Hamilton is the most fog prone major city in New Zealand. After Hamilton, Christchurch is the next foggiest because it is close to the sea, so the air is often very humid.

Fog formation is helped when there are a lot of condensation nuclei in the air. Many of these come from tiny plants in the sea known as phytoplankton. When tiny animals, known as zooplankton, nibble phytoplankton the chemical dimethylsulfoniopropionate is released into the water. There it changes to dimethyl sulphide (DMS) which gets into the atmosphere when breaking waves throw small water droplets into the air, where they evaporate.

In the air, DMS changes to four different chemicals, three of which act as cloud condensation nuclei. DMS also helps make the characteristic smell of the air at the beach.

Fog: Photo copyright Pernell Hartly

Smoke particles can also act as condensation nuclei. Indeed, the celebratory fireworks after the Crusaders victory resulted in a temporary thickening of the fog in Christchurch. During the Napoleonic wars so much smoke was produced by the massed cannon-fire that fog would sometimes envelope the battle field giving rise to the term “the fog of battle”.

Before the clean air laws were enacted, smoke from coal fires and industry used to cause the famous pea-soup fog in London. In December 1952, a notorious fog lasting for days was blamed for 4000 fatalities, mostly from bronchitis and pneumonia. Breathing this particular fog actually caused pain as a portion of the 1000 tons of dirt particles suspended in the London air was sulphur dioxide which combined with water droplets and oxygen to form sulphuric acid.

Some playing-fields in Scotland have underground heating to prevent the soil freezing when frost strikes but there is not much you can do to prevent fog. During the Second World War a lot of effort went into discovering a way of clearing fog from airfields.

The only method that worked, and then only temporarily, was burning petrol sprayed from long pipes either side of the runway so that planes landed between walls of flame. But at nearly 30,000 litres of petrol per landing, it was prohibitively expensive.

Fog is just cloud resting on the ground, and clouds are often found resting on the mountains. So even before night rugby came to New Zealand there was one place where fog frequently turned up before game time and that was the coal mining settlement of Denniston, situated on a plateau 600 metres above sea-level on the South Island’s West Coast.

Although good for fog, Denniston was not a particularly good place for soil and grass. The rugby ground had been bulldozed out of rock and was covered in new load of sand brought up from the beach at the beginning of each season.

Rugby in the fog had certain disadvantages. A ball kicked high in the air, for example, would disappear and players have to wait around for the telltale thump to discover where it came back down.

There was, however, some home advantage. Visiting teams found playing in the persistent fog somewhat confusing, and if the game was going badly for the home team an extra player could be slipped on in the backline to stiffen the defence.

Nor was this astute use of local conditions restricted to the rugby team. An excellent soccer team from Millerton was once unable to make headway against Denniston until the fog lifted, revealing that Denniston had four extra players on the pitch.