Striving for the holy grail of accurate weather forecasting

It’s Weatherman’s Day today. Or Weatherperson’s Day, to be more politically correct. Celebrated mainly in the US, today is the day to recognise people working in the field of meteorology and weather forecasting – those people partaking in the massive task of trying to forecast the weather patterns which, let’s face it, are getting more and more crazy and chaotic each year. The date of 5 February was chosen because it is the birthday of John Jeffries, one of the first weather observers in the US – he collected daily weather data from 1774 to 1816.

Weatherperson’s Day links up thematically with World Meteorological Day that we celebrate in May, but where that day focuses on the weather itself, today we focus on those working to forecast it.

Rain! They said it was going to RAIN! (© All Rights Reserved)
Rain! They said it was going to RAIN!
OK, so the weather forecasters don’t always get it right…
(© All Rights Reserved)

From predicting whether it’s going to rain tomorrow, to developing seasonal weather forecasts, weather forecasting is a hugely complex and computationally intensive endeavour. As such, weather services are often some of the main users of supercomputers around the world. Weather forecasting activities include gathering raw weather data, analysing the data and developing intricate computer models to simulate natural weather systems. One of the (many) challenges of weather modelling is that natural weather and atmosphere systems are near-chaotic – small changes in boundary conditions can result in huge changes in outcome.

These difficulties, however, do not deter the good guys and gals at weather services around the globe who continually strive for more accurate and more timely weather forecasting. According to the US National Weather Service, for example, “lead time for flash flood warnings improved from 22 minutes in 1993 to 78 minutes in 2008. Accuracy over the same time period increased from 71 percent to 91 percent. Lead time for tornado warnings has increased from 6 minutes in 1993 to 13 minutes today. Tornado warning accuracy increased from 43 percent to 72 percent. Winter storm accuracy in 2008 was 89 percent with an average lead time of 17 hours. Since 1990, the Tropical Prediction Center’s 24 to 72 hour tropical storm forecast track errors have been reduced by more than 50%.”

These improvements are quite significant, and can potentially be the difference between life and death for communities in the path of an extreme weather event.

So spare a thought today for all the weather people through the ages who have dedicated their working lives to the holy grail of accurate weather forecasting. After the scorchingly hot, dry weather we’ve had for weeks now, they predicted rain for this week, and lo and behold, it has rained! 🙂

Cloud seeding: Making your own rain and snow

Today, 13 November, marks the date back in 1946 when Vincent J Schaefer, American chemist and meteorologist, performed the first cloud seeding experiment, artificially inducing snow by sprinkling clouds with pellets of dry ice from an airplane.

While this first attempt was not completely successful – the artificially created snow evaporated as it fell through the dry air and disappeared before it hit the ground – it showed that the concept of cloud seeding is possible. This resulted in the GE Research Laboratory (where Schaefer was working at the time) receiving funding for further research into cloud seeding and weather modification.

New Zealand – getting enough rain and snow the natural way!
(© All Rights Reserved)

While initial experiments in cloud seeding was done using dry ice, later substances used include silver iodide, liquid propane and, more recently, salt. Cloud seeding has been done to different extents around the world, in Asia, North America, Europe, Australia and Africa, with China having the world’s largest commercial operation in this domain.

In some of the most recent experimental work in the field of cloud seeding, German scientists at the University of Geneva experimented with firing short infrared laser pulses into the air, the idea being that the pulses might encourage the formation of atmospheric particles which could act as seeding particles in the clouds. According to lead researcher Jerome Kasparian, “the laser pulses generate clouds by stripping electrons from atoms in air, which encourage the formation of hydroxyl radicals. Those convert sulphur and nitrogen dioxides in air into particles that act as seeds to grow water droplets.”

While this work is still at an experimental stage, it has shown promising results in laboratory conditions. A field experiment, where the pulses were aimed at the skies over Berlin, has also shown notable increases in the density and size of water droplets in the area, when measured using weather LIDAR and it is believed that, using the right frequencies and intensities, generation of rain by this means might become a real possibility.

This really feels like science fiction, doesn’t it? Quite incredible to imagine, really!

And of course it immediately reminded me of Kate Bush’s song ‘Cloudbusting’. So herewith, in commemoration of the pioneering work of Vincent Schaefer, father of cloud seeding, the wonderful short film produced for ‘Cloudbusting’ by Kate Bush and Terry Gilliam, starring Donald Sutherland as Wilhelm Reich and Bush as his young son Peter.