Tuesday, February 22, 2011

Earthquake in New Zealand

At 12.51 local time on February 22nd, a powerful earthquake of magnitude 6.3 occurred only 10km from Christchurch in New Zealand.

What has made this earthquake particularly devastating is that it occurred only 5 km below the surface which is a shallow depth.

Although not as powerful as the 7.1 earthquake that hit on September 4 last year, because of its location and depth this event has been far more catastrophic for Christchurch. The September quake was some 40 km from the city at a depth of about 10km below the ground.

The quake was one of the most devastating in the history of New Zealand, producing massive property damage and a death toll that may reach close to 200.

The Pacific "Ring of "Fire". Image from Wikipedia Commons - Click to enlarge)

New Zealand lies on the western branch of the so called Pacific Ring of Fire – a geologically active area that extends from New Zealand up through Tonga, New Guinea, Indonesia, the Phillipines, Japan, and down the west coasts of North and South America.

Earthquakes and volcanic activity are common along this ring but two major earthquakes near Christchurch only five months apart has not been seen before in recorded history.

The tectonic plates of the world -the Pacific Ring of Fire (in purple) follows a large part of the circumference of the Pacific plate. Image from Wikipedia Commons - Click to enlarge)

New Zealand lies across an area where the Australian tectonic plate grinds into the Pacific plate, creating an area of seismic instability.

The collision of these two plates also causes earthquakes around Tonga, Vanuatu and New Guinea.

Thursday, February 17, 2011

The Most Famous Photograph of All

Above - the official Apollo 17 insignia (Image courtesy of NASA - click to enlarge)

"The world, after all our science and sciences, is still a miracle; wonderful, inscrutable, magical and more, to whosoever will think of it". - Thomas Carlyle, Scottish essayist and historian.

The Apollo 17 Space Mission blasted off from the Kennedy Space Centre in the early hours of December 7, 1972, bound for the Moon. The Mission was to be one of the most successful of all time, setting numerous records along the way, including the longest manned lunar landing flight, the longest time in lunar orbit, the longest lunar excursions (using the Lunar Rover vehicle) and the biggest payload of "Moonrock" ever collected. It was to be the last time that man walked on the Moon in the twentieth century.

Despite all these mighty achievements, the Mission is probably best remembered for something else, something much smaller, but destined to become one of the iconic products from all of human spaceflight history.

After a little more than 5 hours into the Mission, Apollo had left parking orbit around the Earth and was on track for the Moon. The fully illuminated disc of the Earth appeared in stunning beauty through the window of the spacecraft, amazing the flight crew of Eugene Cernan, Ronald Evans and Jack Schmitt. It appeared to them as an intricate blue and white glass marble suspended in the black emptiness of space around.

The Apollo 17 crew: from left to right Jack Schmitt, Eugene Cernan (seated) and Ronald Evans. (Courtesy of NASA - click to enlarge)

They were equipped with a 70 mm Hasselblad Camera with an 80 mm lens, and Jack Schmitt pointed this through the window and snapped away. The result was possibly the most famous photograph ever taken, an image that is believed to be the most widely distributed in history.

It showed an entire hemisphere of the Earth bathed in brilliant sunlight - Africa and the Arabian peninsular are clearly visible, as well as various cloud patterns and the sparkling blue of the oceans. And, for the first time, the Antarctic ice cap was photographed from space.

Planet Earth, December 7 1972 (Image courtesy of NASA - click to enlarge)

Soon after returning to Earth, the image was disseminated to the public and became "front page" around the world. Scientists and meteorologists were amazed with the detail revealed and others just marvelled at the beauty of our planet. Here the cradle of life as we know it, from ancient times, to the dinosaurs, to early civilisations, with culture, art, warfare all playing out over the millennia, was laid before us in photographic form.

The image is credited with launching the environmental movement. Earth appears both beautiful but delicate, and many then realised that it was finite and cannot be exploited without limit.

Some of the main features of the image (Click to enlarge)

This photograph became known as "The Blue Marble" and despite the fact that it was taken many years ago, it has never lost its marvel and relevance.

On December 7 2012 it will be forty years since Jack Schmitt aimed his Hasselblad camera through the window and produced this timeless image. I've made a note in my diary so that I don't forget this important anniversary.

See also

Sunday, February 13, 2011

Weather From Space

The first ever image of the Earth taken from space by TIROS 1, on April 1st 1960. (Image courtesy of NASA - click to enlarge)

“We set sail on this new sea because there is new knowledge to be gained, and new rights to be won, and they must be won and used for the progress of all people. For space science, like nuclear science and all technology, has no conscience of its own.

Whether it will become a force for good or ill depends on man, and only if the United States occupies a position of pre-eminence can we help decide whether this new ocean will be a sea of peace or a new, terrifying theatre of war.”

President John F. Kennedy
Rice University Stadium
Houston, Texas
September 12, 1962

Since the launch of the first meteorological satellite, Tiros 1, in 1960 there has been a steady proliferation of “eyes in the sky”, constantly sending back to earth images of the weather far below.

Most of these “eyes” are unmanned space vehicles, equipped with increasingly sophisticated instrument packages, which not only perform weather photography but can also undertake many other scanning functions, such as the monitoring of crops
and the tracking the movement of mosquitoes across continents.

Some of these are polar orbiting satellites, and others are in geostationary orbit, but all are vital sources of environmental data, and are constantly used by a diversity of Government and non-Government agencies.

Manned space vehicles have also been used to photograph the Earth from above, and these images have been collected from the early days of the Mercury Project (1961 to 1963), all the way up to today’s regular Space Shuttle flights. Although some of the older images in this category date back more than 40 years, their relevance and sheer majesty remain as important today as when they were first taken.

Image taken from Gemini 7, November 13 1966, above Baja California (Image courtesy of NASA - click to enlarge)

The USA Manned Space Program

Much of the early manual photography from space was not intended to highlight the weather, but was more focussed on landforms and cities, as well as on-board tasks and activities.

However, many of the photographs taken, which were not intended for meteorological purposes, still contain some fascinating images of weather phenomena.

The entire program can be divided into the time series

Mercury Project Flights 1961-63
Gemini Project Flights 1965-66
Apollo Project Flights 1968-72
Apollo-Soyez/SkyLab 1973-75
The Space Shuttle Pre-Challenger 1972 – 1988
Space Shuttle Post-Challenger 1988 – present

The USA manned space flight program began in 1961 with a Mercury Project sub orbital flight commanded by astronaut Alan B. Shepard, Jr, in his “Freedom 7” spacecraft, and then expanded rapidly, culminating with the “Man on the Moon” Apollo missions, which ran between 1968 and 1972.

Official portrait of Alan Shepard taken 12 December 1963, dressed in his Mercury pressure suit and holding his space helmet. (Image courtesy of NASA - click to enlarge)

Photographs of the Earth taken by astronauts on these missions created a sensation in scientific circles, as well as for the general public, and were widely disseminated in newspapers, magazines and in special issue collections of boxed slides.

When the “full Earth” images from the Apollo Projects appeared, unprecedented world wide interest was generated, and the fabulous “Earth rise” photographs, showing the Earth appearing above the lunar horizon, would surely be one of the most famous series of images ever taken.

View of the Earth “rising” over the Moon's horizon, taken from the Apollo 11 spacecraft on 16 July 1969. (Image courtesy of NASA - click to enlarge)

The tradition then continued with the Apollo-Soyez/SkyLab projects, which were launched between 1973 and 1975, right through to the Space Shuttle missions of today.

All these photographs are still of considerable interest to the meteorologist, as many weather phenomena, such as hurricanes, cold fronts, low pressure cells, jet streams and thunderstorms were brilliantly captured, contributing greatly to our knowledge of the structures of these systems.

Unmanned Space Vehicles

While the manned space program was under way, an ever increasing number of unmanned vehicles was also launched, and many of these were designed for specifically monitoring the weather, and in recent times, more general aspects of the environment.

From the vague, primitive imagery of Tiros 1, we have progressed to high-resolution photography of astonishing detail, in which information from meteorological satellites has been augmented with that from broader function “environmental” satellites.

There are two general varieties of these satellites.

(a) Polar-orbiting vehicles, which take measurements from an altitude of between 250 to 850 km, (~155 to 525 miles) scanning over several different wavelengths.

Such satellite images provide information on a wide variety of weather phenomena, including the extent of fog, floods, snow cover and sea ice, sea surface temperatures and ocean waves, temperatures, humidity and pressures throughout the troposphere, and on upper wind speed and direction, which can be derived from cloud movements.

The images also display cloud formations associated with hurricanes, cold fronts and jet streams, and can also capture smaller scale features such as mountain waves and von Karman vortices, caused by disturbed airflow around raised features such as islands.

Intricate von Karman vortices produced by winds blowing around the Cape Verde Islands off north-western Africa.
(Image courtesy of NASA - click to enlarge)

(b) Geostationary satellites, revolve around the earth at a height of 36,000 km (22,320 miles) over the equator at the same speed as the earth turns – a feature which is called “solid rotation”.

Successive images provide a moving picture of clouds as they form, are carried by the winds, and finally dissipate, enabling estimations of wind speed and direction at different altitudes in the atmosphere to be calculated. This is of vital importance in forecasting the speed of movements of such phenomena as cold fronts, low pressure cells and hurricanes.

Several different countries have launched their own meteorological satellites, including both the polar orbiting and geostationary varieties. These include METEOR (Russia), NOAA (USA), METEOSTAT (Europe), GOES-E and GOES-W (USA), GMS (Japan), FENGYUN (China) and INSAT (India).

Environmental satellites

In very recent times, the next generation of environmental satellites have been launched, and these are providing dazzling images of a variety of global phenomena, including very high-resolution views of the weather.

The USA Earth Observing System (EOS) satellites Terra and Aqua, carry the MODIS (Moderate Resolution Imaging Spectroradiometer) package, which is a key instrument in monitoring climate change through the observation of sea ice, glacier extent and ocean levels.

Another USA environmental space vehicle is SeaStar, which carries the highly advanced SeaWifs (Sea-viewing Wide Field-of-view Sensor) package. This is designed to monitor and study the role of oceans in determining our climate, including the exchange of critical elements and gases between the atmosphere and ocean, and how these exchanges affect microscopic marine plant (phytoplankton) production.

A dust-storm from out of Africa blows across the Mediterranean towards Sicily to western Greece. (Image courtesy of NASA - click to enlarge)

In performing these diverse functions, MODIS and SeaWifs have also captured some amazing weather-related images that have contributed substantially to our knowledge of the weather and the effects that it produces.

The role of the US National Aeronautics and Space Administration (NASA) cannot be overstated here. Imagery collected from NASA space programs has always been made freely available across the Internet and this has revolutionised public understanding of the structure of our atmosphere. It has also provided educational material of tremendous value to everyone around the world and greatly increased public interest in the science of meteorology.

Some great weather imagery can be accessed from the following NASA web sites:



See also:


Sunday, February 6, 2011

Weather Station "Kurt"

Weather forecasting has improved steadily over the last thirty years or so, and there are probably three main reasons for this. Firstly we have vastly improved access to satellite imagery, with increasing frequency and quality becoming available. And then mathematical modeling of the weather using ever more powerful computers has advanced considerably during this time. And, tied in with this, is the continually expanding network of automatic weather stations (AWS’s) that provides high quality observational data for input into the forecasting process.

Above: A technician services the sensor of an automatic weather station. (Image: Wikipedia Commons - click to enlarge)

AWS’s are high tech instruments providing a continuous stream of weather information that is channelled into computers to power the mathematical models used for weather prediction. Consisting of a “black box” packed with electronics and sensors, they provide measurements of temperature, humidity, rainfall, barometric pressure and also wind speed and direction and then transmit this information back to a main meteorological centre.

An automatic weather station being installed in Antarctica (Image Wikipedia Commons, William N. Connolley - click to enlarge)

They can be powered by solar cells in remote locations, or, if a suitable source exists, from mains electricity.

It is generally assumed that AWS’s are modern instruments but a surprising find emerged in the late 1970’s when a retired German technician Franz Selinger, began writing the history of the Siemens Company, and discovered old files indicating that during World War 2 Siemens had manufactured a type of automatic weather station called Wetter-Funkgerat Land (WFL) with twenty six of these eventually built.

The Germans had needed weather information from around the Atlantic Ocean to plan their U-Boat operations and had intended to install WFL units at various locations that would transmit weather data back to Germany by radio. Then further research revealed an amazing story that had occurred during the war but had been almost totally forgotten in the mists of time.

In 1943, the German submarine U-537 departed from Kiel carrying a normal combat crew, but also a meteorologist Dr. Kurt Sommermeyer and a Siemens WFL unit codenamed “Weather Station Kurt”.

In a top-secret James Bond style operation, U-537 arrived in a remote area called Martin Bay in far northeastern Canada, and an armed party, accompanied by Sommermeyer, went ashore and successfully installed WFL “Kurt” on a rocky outcrop before departing without detection. It is believed that this was the only enemy landing on North American soil during the Second World War. Some idea of the remoteness of Martin Bay can be seen in the last photo of the series at


The battery powered “Kurt” was designed to transmit weather information in code every three hours and this it did, although the data flow ceased after only a few days. This could have been a technical malfunction or the result of radio jamming by Allied forces.

“Kurt” was then forgotten but following Selinger’s research a possible location was revealed. In 1981 the Canadian Coastguard investigated, and to everyone’s amazement, rediscovered “Kurt” standing alone on the rocky knoll where it had been installed 38 years before. Canadian technicians were surprised at the highly advanced array of meteorological instruments and supporting telemetry systems that were built into “Kurt” – it compared well with even modern automatic weather stations.

The instrument was then restored and is currently located in the Canadian War Museum in Ottawa.

Weather station "Kurt" today showing the instrument masts and battery canisters painted in military camouflage livery. (Image: Wikipedia Commons - click to enlarge)

Friday, February 4, 2011

"Yasi" versus "Tracy" - A Tale of Two Cyclones

Severe tropical cyclone "Yasi" smashed across the north Queensland coast near Mission Beach, just to the south of Innisfail, around midnight on 2nd February. Producing wind gusts in excess of 200 kph, massive oceanic storm surges and torrential rain, it cut a trail of destruction through the area, with hundreds of houses destroyed or damaged, marinas smashed, massive dislocation of infrastructure and a devastation of Queensland's banana industry.

Above: Tropical cyclone "Yasi" approaches the Queensland coastline on 2nd February 2011. (Image courtesy of NASA, USA, click to enlarge)

Some 37 years before, on Christmas morning of 1974, tropical cyclone "Tracy" had stormed across Darwin, flattening a large area of the city and cutting off communications with the rest of the world for some six hours.

Both cyclones were probably of similar strength although "Yasi" was a far larger cyclone in area than the compact "Tracy".

Satellite imagery of "Tracy", Christmas morning 1974. Comparison of this with the image above of "Yasi" shows the progress made in this area. Only two such images were received every day in 1974, and now they are available every hour. (Image courtesy of NOAA, USA)

But when comparing these two major disasters there is one vastly different outcome. 65 people lost their lives in "Tracy", and at the time of writing there are no known deaths attributed to "Yasi" although two people remain unaccounted for. But why is this so?

Firstly, weather prediction in general, and cyclone prediction in particular, has improved enormously since 1974. The availability of higher quality and more frequent satellite imagery, together with information from a larger number of automatic weather stations, has made a big difference.

Devastation across Darwin produced by Tracy in December 1974. (Image from Wikipedia Commons - click to enlarge)

But one of the major factors is the progress in computer simulation of the atmosphere. The predicted tracks of tropical cyclones have become increasingly accurate, with useful warnings now issued up to a week ahead and this allows the population in affected areas to be well prepared.

An interesting example here concerns the week before "Yasi" when tropical cyclone "Anthony" formed off the north Queensland coast. The computer simulation predicted that it would then move southeast, before reversing direction and heading back towards the coastline. And this is precisely what happened, with the highly erratic path accurately predicted by Queensland meteorologists. This type of forecast was well outside the capabilities of meteorology in 1974.

And then there are the social factors - public education about tropical cyclones has raised awareness of the dangers of these systems and warnings are regarded far more seriously than in 1974. In the run up to "Tracy" warnings for tropical cyclone "Selma" were issued, but this system passed just by Darwin with little impact. For many this proved that weather forecasters "always got it wrong" and subsequent warnings for Tracy were largely ignored.

The role of NASA should be mentioned here - NASA is the acronym for the US based National Aeronautics and Space Administration, and NASA satellite imagery, such as that of "Yasi" above, is made freely available across the internet. This has been of immense value in raising interest and providing educational background to severe weather events such as cyclones and is therefore an enormous contribution. NASA's image web site can be found at


The nature of the media has also changed. Television, in particular, will only run a story if "vision" is available and many severe weather events of the past were not covered for this reason. Now we have widespread availability of mobile phones that can take stills and movies good enough to use. This has revolutionised television coverage of severe weather events. Social media such as tweets, twitter and blogs have also produced major impact in raising community readiness.

Back in 1974, tropical cyclones were not big news in the southern states until they actually hit - now we have massive national media coverage well in advance, with The Weather Channel, I'm proud to say, playing a leading role.

The Weather Channel's satellite display showing the remnants of "Yasi" moving across northern Queensland.
(Click to enlarge)

The integration of meteorology with State emergency services has advanced considerably. This ensures that people are warned early, evacuated from areas of danger, and also allows the recovery to be managed more efficiently.

The use of the Press Conference, involving in this case the Premier of Queensland Anna Bligh, before the cyclone struck, and then during the aftermath, was also of immense value, and more than likely has saved lives and reduced property damage.

The considerable sum invested by Australia in the area of tropical cyclone warning and prediction has been more than worth it, and will continue to produce positive outcomes in disastrous situations.

In early 1975 the Australian duo "Bill and Boyd" composed the following song as a fundraiser for the victims of "Tracy" - it's a rare example of a song composed in response to a weather disaster.


For some thoughts on how weather prediction has evolved over the centuries go to


Tuesday, February 1, 2011

Fu-Go - The Balloon Bombs of Japan

One of the most remarkable weapons of the Second World War was the so-called Japanese balloon bomb or “Fu Go” that was an early example of using the winds in the upper atmosphere to conduct a military attack.

During the latter stages of the war, people in various parts of the USA became aware of sudden explosions that appeared to be taking place in random fashion across the country. Little damage was done but the US Military, particularly the Air Force, became increasingly interested.

After investigating the site of one such explosion they made an astonishing discovery. It appeared as though the explosions had been caused by bombs carried by some type of lighter than air balloon - and a very large one at that. It was calculated that the balloon in question was, when inflated, about 10m (33 ft) in diameter.

Above: A captured Fu-Go balloon relaunched by the American Military for research purposes. (Image from Wikipedia Commons - click to enlarge)

By examining the sand ballast attached to the object they were able to establish that the sand came from Japan and that the balloon was filled with hydrogen. Furthermore it was found that the balloon itself was made from a special type of paper called washi – a Japanese product.

It was realised that the Japanese were launching bomb-carrying balloons from Japan, and these were climbing to an altitude of around 10km where they were picked up by the upper level jet stream that carried them across the Pacific Ocean to the United States. After a journey of around three days the balloons arrived over North America and the bombs, usually consisting of incendiary and antipersonnel devices, were jettisoned automatically.

Left: The Fu-Gos were carried across the Pacific Ocean from Japan to North America in the upper air jet streams. A typical journey took three days. (Click to enlarge)

Jet streams are high speed rivers of air moving from west to east in the upper levels of the atmosphere and occur as a result of temperature differences and the spin of the Earth. Wind speeds in excess of 250 kph (155 mph) sometimes occur.
The jet stream made visible by cloud. This view taken from the Space Shuttle, shows the jet stream across eastern Canada in May 1991. (NASA image - click to enlarge)

Normally there are four such streams, two in each hemisphere, called the polar jet and subtropical jet and these tend to move in waves around the Earth. These jets also move north and south according to the seasons and affect different parts of the USA at different times of the year.

The US Government wanted to avoid public panic and ordered that the presence of the balloons be kept secret, but after a family was killed by an explosion in Southern Oregon, warnings were issued to the public.

Between November 1944 and April 1945 the Japanese launched some 9300 balloons with around 300 reaching the USA. Bombs were dropped over widespread areas including Alaska, Washington, Oregon, California, Arizona, Idaho, Montana, Utah, Wyoming, Colorado, Texas, Kansas, Nebraska, North and South Dakota, Michigan and Iowa, as well as Mexico and Canada. Interestingly there were a few cases where the balloons missed their mark and circumnavigated the globe, crossing back over Japan after a week or so in the air.

Government authorities were particularly worried that the incendiary bombs could trigger forest fires and even more by the possibility that the balloons could be used to introduce biological agents and livestock diseases into the USA. Fighters were ordered to intercept and shoot down the balloons wherever possible but after B29 bomber raids destroyed two of Japan’s main hydrogen producing plants in April of 1945, the Japanese abandoned the offensive.

Left: Gun camera footage of Fu-Go's being shot down by American fighters during the latter stages of World War 2. (Image from Wikipedia Commons)

The Fu Go balloon bomb would go down in the history books as a fairly ineffective device but it produced widespread concern across the USA and was one of the very few times the mainland of North America was actually attacked by an enemy during armed conflict.