I have to say that this summer is, weather-wise, the most pleasant summer in memory by some margin.

Perhaps an antidote to much of the unpleasantness that surrounded 2020?

I recently travelled across to Tamworth, something I do only quite rarely, and so was struck by the incredible contrast to this time last year.

Instead of brown dirt for much of the trip and the occasional straw of dehydrated plant matter, there was lush green the entire way.

Cotton, sorghum, corn – all crops and pastures were flourishing.

Farmers were breaking out slashers from long stints in confinement to mow along the verge of the roads.

Near Gunnedah the grass was so high and lush it was actually a safety hazard near one bend in the road.

Stock were lazily grazing in the mild summer sun.

Here in Narrabri it has been warm and humid.

I cannot think of a day in the last few weeks when the sound of a lawn mower has not been heard.

I have given the old Victa a significant work out since Christmas and there is probably more to come.

A couple of years ago we went almost two months with every day topping 38 degrees.

This summer, since early December, we have not even reached that mark.

I have wondered why this might be? Why is there such a contrast to previous years? Especially the nationwide inferno of last year.

The memory of the bushfires and of the anger at Scott Morrison for his ill-timed break in Hawaii seems a very long time ago.

I am reliably informed (by Graham Creed the ABC weatherman) that the phenomena we have to thank is “La Nina”.

Now this nugget of intelligence caused me to nod my head in what I hoped was an intellectual manner and say something like “aaahhh, La Nina, well that explains it!”

As well it did.

But it didn’t.

Because, perhaps like you, I had only the slightest idea of what La Nina actually is. Something to do with the Pacific Ocean, I would have guessed. But then I would have stumbled into silence, as that was the extend of my – clearly limited – understanding.

So, dear reader, in order for you to be able to make far more intelligent noises than I would have, if asked about La Nina, I offer you the results of my considerable googling efforts.

As you may know, El Nino and La Nina are (somehow) related. Basically, it seems they are two sides of the one coin. That coin being wind patterns in the Pacific Ocean.

These wind patterns have a big impact on our weather.

Across the almost unimaginable expanses of the Pacific, trade winds blow most of the time.

These winds blow east to west. Basically, from South America across to Asia.

They pretty well always blow. It’s how strongly they blow that is the issue.

In a La Nina cycle, such as now, the trade winds blow quite strongly. That’s important. Because everything is connected.

The strong La Nina trade winds push more warm surface water west, towards Indonesia and Asia, just north of Australia.

It creates something like a giant warm river running east to west through the Pacific.

Warm water evaporates more easily than cooler water. (Think how steam rises as an extreme example.)

This results in a lot more water in the atmosphere in our region.

More water in the atmosphere means more humidity, more rain and less extreme temperatures.

Believe it or not, water is one of the most effective natural insulators. Therefore, nights are warmer and days cooler.

The sticky humidity is the price we pay for this.

Basically, all El Nino is, is a weakening of the trade winds and a reversal of what I just described above.

So, we have to thank for our beautiful mild summer and burgeoning crops, some winds that start over near Chile.

And that’s all I can tell you, because Mrs Doyle has kindly reminded me that the lawn needs to be mown…again.

Bill Doyle, The Courier’s occasional guest columnist.

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