Christmas past

Written by Georgina Griffiths, Meteorologist

Christmas Day in New Zealand can be a hit and miss affair, weather wise. Some years, a High arrives in time for Santa. Christmas Day 2009 was beautifully fine and warm across the country, with Dunedin hitting 32°C, and many other centres approaching  25°C.

Radar and mariners – a long relationship

The development of modern radar started in 1886, when German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1904, another German, Huelsmeyer, was the first to build a simple ship detection device, successfully detecting a ship in dense fog. In the pre-war period (the 1930s), many nations were working on radar devices. A major advance occurred once systems were developed that allowed short ‘pulses’ of radio energy to be generated, allowing the range of the object to be determined by timing the pulses.