Up, up and away in my beautiful, my beautiful balloon… So the song goes, but what’s it actually like way up high in the atmosphere? Could we humans live up there if we wanted to, or had to? I recall David Attenborough doing a great documentary in the series “The Living Planet” (“The Sky Above” episode, BBC) where he ascended beneath a very large hot-air balloon, complete with oxygen mask and equipment for sampling for life specimens. It was surprising to discover that small insects could be whisked up there and freeze, before descending again and reviving.

In the days following Wednesday 6 July 2011, stormy westerly conditions affected New Zealand. In this blog, we'll look at why.

The "Long Waves"

Below is the mean sea level analysis - the weather map - for 6am Sunday 10 July. In between big highs over the mid South Pacific and south of western Australia is a really large trough; it's the area shaded light blue. The weather map looked like this, more or less, since Wednesday 6 July: that is, the big features on it aren't moving much.

In New Zealand, most people would not consider May and October to be winter months. This year, however, they were noticeably colder than usual. NIWA remarked upon this in their Climate Summaries for May and October 2009. To quote very selectively from these summaries:

If you were in New Zealand in the mid '70s you may remember a particularly strong wind-storm that devastated many parts of the eastern South Island. It struck on 1 August 1975, doing a huge amount of damage to pine trees in the Eyrewell and Balmoral forests in particular. To give you an idea of the power of this storm, some of the peak recorded winds and gusts were:

 mean wind (including gusts and lulls) strongest gust Christchurch Airport 126 km/h172 km/hTimaru Airport130 km/h165 km/hEyrewell Forest119 km/h170 km/h