Nathan and other cyclones

People who live in North Queensland learn to keep an eye on cyclones as long as they exist, whether they look like being a direct threat or not. I followed the progress of cyclone Nathan, via the BoM’s Cyclone Tracker, day by day and it turned out to be a good example of their unpredicability.

The thumbnails here are screen shots from the BoM site at around noon each day from Monday 16 March until Nathan was declared ‘no longer a cyclone’ on Wednesday 25 March; click on them for larger images, as usual, or a slide show. A satellite image showing Nathan’s remnants off the Kimberley coast on Saturday 28 March completes the sequence.

Nathan, March 16

Nathan, March 16

By the time I started recording Nathan, the cyclone had formed in the Coral Sea, drifted slowly West towards Cooktown, stalled, back-tracked slightly further North and drifted South and East to be almost exactly East of its position five days earlier. The prediction at that stage (March 16) was for intensification from category 2 to 3 and a track to the South and West which might have struck the coast anywhere between Cairns and Cardwell a few days later.


Nathan, March 17

Nathan, March 17

Nathan, March 18

Nathan, March 18

Nathan, March 19

Nathan, March 19


In the event, Nathan tracked further to the North, crossing the coast just North of Cooktown as a category 4. When a cyclone moves over the land, it loses its source of energy and moisture. Wind speeds fall quickly and the storm can be downgraded from (e.g.) category 4 to 2 in a matter of hours and, if it stays over land, to a tropical low or rain depression.

Nathan, March 20

Nathan, March 20

A rain depression can still be a very significant weather event, with hundreds of millimetres of rain falling in 12 or 24 hours, but without the destructive winds.

Townsville’s “Night of Noah” in 1998 was one such event, the result of the remnants of cyclone Sid; it brought us a metre of rain in a day or so, more than enough to stick in the memory. Wikipedia has quite a big page on it, and the BoM produced a comprehensive report (pdf).


Nathan, March 21

Nathan, March 21

If the weather system moves back to sea, however, it can re-form into a cyclone. Nathan did just that after crossing Cape York, and struck the Eastern tip of the Northern Territory during the night of 21-22 March as a category 2 system.
The people of Nhulunbuy must have felt life was totally unfair, since they had suffered through cyclone Lam (bigger but not striking them so directly) only a month earlier.


Nathan, March 23

Nathan, March 22

Nathan, March 24

Nathan, March 23

Nathan, March 24

Nathan, March 24


After passing very briefly over land, Nathan tracked West along the Arnhem Land coast, just far enough out to sea to pick up more energy and remain at category 2, before dipping South-west over Maningrida on March 24. That was its last day as a cyclone. It continued over land to the South-west, passing South of Darwin and then out to sea as a low. It dumped 100 – 200mm of rain on the way, flooding remote communities and cutting roads.

The remnants of Nathan off the Kimberley coast, March 28

The remnants of Nathan off the Kimberley coast, March 28

Four general points about cyclones are worth making:

  • The Bureau of Meteorology does a terrific job of tracking and predicting cyclones. Predictions for 24 hours ahead consistently come true, and the cyclone’s track further into the future stays within the widening grey cone of possible tracks.
  • How much damage a cyclone does to human life and property depends as much on its track as on its strength. When Nathan crossed the coast North of Cooktown as a category 4, its footprint covered Cooktown (pop. 2500) and a few smaller communities – a total of perhaps 5000 people. When cyclone Larry crossed the coast near Innisfail (pop. 8500 and in a much more closely settled region) in 2006 as a category 4 it did $1.5 billion worth of damage.
  • Cyclones (typhoons) striking areas with greater population density, e.g. the Philippines  (and especially Haiyan), or less-robust infrastructure, e.g. Cyclone Pam in Vanuatu  often have far more dire effects.
  • Climate change fuels stronger cyclones. According to Kerry Emmanuel on RealClimate there is a “strengthening consensus that the frequency of high category tropical cyclones should increase as the planet warms.”

Basic theory and a variety of numerical simulations support this, as well as the projection that tropical cyclones should produce substantially more rain, owing to the increased moisture content of the tropical atmosphere. This is important because most destruction and loss of life are caused by high category storms and their attendant storm surges, and by freshwater flooding from torrential rains. Most of the disagreement in the literature on tropical cyclone projections concerns the incidence of weak storms, but these are usually far less consequential in spite of being more numerous.

… While Pam and Haiyan, as well as other recent tropical cyclone disasters, cannot be uniquely pinned on global warming, they have no doubt been influenced by natural and anthropogenic climate change and they do remind us of our continuing vulnerability to such storms.

Posted in Climate change, Technology | Tagged , | Leave a comment

Outstanding wildlife photography on show

Snowbird

Snowbird

The Museum of Tropical Queensland is hosting a great travelling exhibition at the moment  – prints from the 2014 Wildlife Photographer of the Year award presented by the Natural History Museum and the BBC. It opened in Townsville on March 21 and will be on display until May 17. It is one of the world’s top competitions so it’s no surprise that the photos are amazing for both content and technical excellence.

What I noticed, time after time, was the effort and persistence expended by the photographers in their quest for the perfect shot: putting the camera lens within inches of a flow of molten lava to capture surface details, setting up a series of infra-red photo traps in the Hollywood hills and waiting for a year before to get a good shot of a cougar, diving with sharks, travelling with tribal lion hunters in Africa – whatever it took. The photo at the top of this page was achieved comparatively easily:

Cheese and sausage are what Siberian jays like, so Edwin discovered on a skiing holiday with his family in northern Sweden. He dug a pit in the snow deep enough to climb into, scattered the food around the edge and waited.

I doubt that I will ever be inspired to go even that far, but I may be inspired by the beauty and drama found in some of the more accessible subjects. It should challenge me for about the next twenty years, actually.

I may not have bothered to write here about the show (its limited time and single location mean that it won’t be relevant for many readers) except that prints from the NHM in London can be previewed and ordered online – click here to see some and, if you like, acquire them.

Posted in Nature photography | Leave a comment

A sunbird takes a bath

Sunbirds (Nectarinia jugularis) are our prettiest small birds and we are always delighted to see them in our garden. They don’t seem to live here (I blame our cat for that!) but a couple living nearby visit fairly often. I have seen them foraging for food and collecting nesting material, and this morning the male came for a bath when I turned on the sprinkler in his favourite part of the garden.

small bird with yellow belly, blue bid and olive back

Olive-backed Sunbird

same bird

A chance to dry off and look around

He flew up to a higher branch after a while, to stretch and dry off, but soon returned. A Brown Honeyeater (Lichmera indistincta) thought a bath was a good idea, too, and joined the sunbird for a while.

grey and olive bird on twig

Brown Honeyeater

wet grey-green bird

Having a good shake

But the Sunbird stayed longer, still enjoying himself under the sprinkler after the Honeyeater left.

Posted in Birds | Tagged , | Leave a comment

A very small drama on Castle Hill

Castle Hill from the Magnetic Island ferry

Castle Hill from the Magnetic Island ferry

Castle Hill is an immense mass of pink granite rising above the city. Beloved by tourists, joggers and landscape painters, it is a challenging environment for wildlife because the soil (where there is any) is so thin. Rainwater drains off almost instantly, so the vegetation struggles to survive and there aren’t many herbivores to feed the carnivores. Nevertheless, on Sunday I spent almost an hour in a little patch of open scrub near the summit, watching to see what was around, and was well rewarded.

There were grasshoppers, butterflies (Blue Tigers, Migrants, Crows and a few others), a couple of bee-flies, a baby mantis and lots of ants (links here take you to these insects on my flickr photostream), but the spiders drew my attention. There were odd little patches of silk in a few seed-heads of the tall grass and I pulled one apart to find a small pale-gold spider, while a similar but bigger patch in a knee-high sandpaper fig tree was home to what looked like a whole family (a female guarding her egg-sac and a smaller adult which could have been the male) of grey-brown spiders. A slim grey spider with enormously long legs appeared on the trunk of a poplar gum and wandered off again, and I watched the later stages of a deadly attack on one spider by another.

The attacker was a jumping spider (Salticidae, perhaps a Sandalodes) and its prey was a Lynx (Oxyopes macilentus). Both are predators, but the Lynx is an ambush hunter, typically waiting for prey to come within reach, while jumping spiders are roving hunters. In this case it looks like the jumping spider, the larger of the two, had chanced across the Lynx and lived up to its name; the Lynx offered very little resistance to its larger attacker.

How big are they? Not very big at all: perhaps 11 mm and 7 mm. If I hadn’t chosen to sit quietly and look around,  I wouldn’t even have noticed them in the grass.

two spiders

The jumping spider already has the advantage

two spiders

Nearly over. The Lynx has lost a couple of legs

two spiders

It’s easy to feel sorry for the loser

Posted in Insects and spiders | Tagged , , , | Leave a comment

Snowpiercer

snowpiercerSnowpiercer came to Townsville yesterday, as Townsville Cinema Group’s first movie of the year.

At its most bare-bones level, the plot is about a near-future climate apocalypse and its aftermath. In response to global warming, governments seeded the planet’s skies with particles to block some of the sunlight reaching the earth’s surface and bring temperatures down to liveable levels, but they got it catastrophically wrong and threw the world into an ice-age. The last remnants of humanity are gathered in a sealed community with an autocratic leader, a decadent upper class, a subservient working class, a desperately poor underclass and a small army of amoral goons keeping everyone in their proper places. This is the setting for the movie’s main story, which follows a revolt of the underclass against their faceless, heartless ruler.

So far, the scenario is not, unfortunately, completely implausible. Global warming is all too real and geo-engineering, as described in the movie, has been seriously proposed by people with expertise in the field (and rightfully howled down by people with more expertise and common sense). And examples of brutally stratified communities controlled by more-or-less crazed dictators are all too common, as are revolts of the have-nots against the haves.

Once we move from generalities to particulars, however, implausibilities pile up faster and thicker than snowdrifts in a fimbulwinter blizzard. The sealed community, you see, is a train – huge, magnificently engineered and impressively fitted out, admittedly, but a train. Circling the globe on a grand loop of tracks purpose-built for it by its visionary engineering-tycoon creator (yes, we’re in mad-scientist territory here, folks), Snowpiercer hurtles endlessly through a wilderness of snow and ice.

If viewers can suspend their disbelief about the back-story, they can enjoy a well-crafted conventional against-the-odds action movie as our underclass hero gathers followers, plans his revolt and fights his way from the rear of the train to the ruler’s quarters at the front. It’s well done but, aside from the setting, not particularly new or original; Spartacus will serve as its archetype, just as 20,000 Leagues Under the Sea might serve as the archetype for the autocratic-mad-scientist meme. This last reference, incidentally, is apt in another way, since Snowpiercer has affinities with steampunk (choose an entertaining  or pedestrian explanation of steampunk if the term is new to you).

Do the implausibilities matter? I think that depends on whether the film has any claim to be taken seriously. If it’s just another action movie, who cares? If it is to have any credibility as a comment on our social and environmental stupidity, however, it must have some integrity, at least on its own terms. Good science fiction movies (they are rare but The Matrix comes to mind) do that; bad ones (which are far more common) don’t. Rotten Tomatoes liked Snowpiercer very much but IMDB wasn’t quite as keen and neither, for what my opinion is worth, was I.

Townsville Cinema Group screens good non-commercial movies at Warrina every fortnight. If you live in Townsville but haven’t already got it, look at their programme for the first half of the year and think about joining or, if you like, just dropping in and paying to see those which particularly appeal.

Posted in Climate change, Film | Leave a comment