Back when Longy use to get wind a lot the beach looked like this.



Sam.

Hi Sam, the pic shows that we have stabilised the lagoon entrance configuration and the dunal areas. But I don't think it explains our change in wind strengths on the northside since then.

I wonder if its something to do with the increased amount of building and concrete in sydney somehow forming a heat sink (the hot air stays in the concrete instead of rising) that reduces the seabreeze on the north side and has subsequently increased it on the edges (central coast and Wanda) as it funnels around the city ??

Any other hypotheses ??

Rob

Another point is the water/land temperature

I believe a seabreeze needs a temperature differential between water and land temperatures, so as the land heats up during the morning, the heated air rises and sucks the cooler air in from the sea.

Water temperatures are warmer now than 20-30 years ago, across all seasons, and the "heat island" effect of development means overnight temps in summer are warmer.

Therefore, if the land temperature warms during the day from a higher base temperature the previously, then the air doesn't rise as fast, plus if the water temperature is also higher as well, the water/land temperature differential is much less, so a reduction in sea breeze strength results.

Just a thought.

Cheers!

Both very good Points - something I have been arguing for a long time now.

You will also notice that the direction of the NE has changed considerably since the 80,s when it was more East.

At palmy we used to be able to sail from south of the golf course to the western side of BJ in one tack. Also at the lake you could sail at the tin shed and you course was along the sand bar.
Same at the bay in a NE you would sail paralell to the runway

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KA643 said...
I wonder if its something to do with the increased amount of building and concrete in sydney somehow forming a heat sink (the hot air stays in the concrete instead of rising) that reduces the seabreeze on the north side and has subsequently increased it on the edges (central coast and Wanda) as it funnels around the city ??

I have also been wondering about this for a long time. When you go up to the top level of the Bondi Junction Shopping Mall you can clearly see that there is a long gradual drop from there right down to Botany Bay/ Wanda Beach. The other side towards the harbour on the other hand is a short and steep rise.

I think the effect is that NEer air flow is compressed and slowed as it climbs up over the hill. That energy is then released as the air accelerates down the other side towards Botany Bay and Wanda. The build up of Bondi Junction with lots of concrete that heats up in summer could have enhanced that effect.

Perhaps the build up of Dee Why created a similar effect there just on a smaller scale which could result in the airflow along Long Reef Beach being slowed down.

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KA643 said...

Hi Sam, the pic shows that we have stabilised the lagoon entrance configuration and the dunal areas. But I don't think it explains our change in wind strengths on the northside since then.

I wonder if its something to do with the increased amount of building and concrete in sydney somehow forming a heat sink (the hot air stays in the concrete instead of rising) that reduces the seabreeze on the north side and has subsequently increased it on the edges (central coast and Wanda) as it funnels around the city ??

Any other hypotheses ??

Rob

That would be the Urban heat Island Effect Rob there is alot of research that has come out of Canada on how cities are impacting the climate. Dry but very interseting stuff.

That's why migrating to smaller regional cities is the only way to go.
No air-flow problems down here.

Great pic though. I can see my old house.

thanks for rubbing it in Carl !

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KA643 said...

thanks for rubbing it in Carl !

Just trying to contribute my theories on local weather behaviour

No doubt about it the sea breeze in and around Sydney is definately not what it use to be..... You know what to do to solve the problem???????? Hook up with a good WA girl and move to WA !! We have just had cracker of a season!! More wind than you would poke a hair dryer at.