Topic: Deadspots!

[David Brodrick]

Thanks for the good responses RE vegetation further up the thread Michael/Mike. I'll relay the gist of your comments onto the person who asked me about the bushfire/storm relationship.

My (completely ignorant/uninformed) thinking would be that while vegetation is a factor that contributes to storm development, I wonder if it's lost in the noise to compare big factors such as a high in the Tasman forcing moist air over NSW.

However did you see the lighning doco on ABC last night? They've done research which shows that there is more lighning over Houston than the surrounding areas, attributed to the heat generated by the city, so the local effects clearly do play a role which is significant enough to be measured. Also I guess the bushfire was 150,000 Ha which is a fairly substantial slab of dirt.

Regards,
  Dave

[Mike]

hey Dave.

Well on a similar vein they reckon that parts of WA where there's a lot more iron ore in the ground is a great magnet for CGs.  My uncle worked out bush there and he said it was phenominal the amount of lightning those particular 'hot spots' attract. 

There are certain parts of the NT outer darwin area that get more rainfall that Darwin City's average.  Acacia is around 60 or 70km down the track and they get the most rainfall at any stage during the wet or dry and the topography is relatively flat but with 'undulating hills' (we dont have mountains in NT!!!!)

We mortals do have a nasty, cancerous habit of changing weather patterns due to 'progressing onward' without the long term regard for present day and future generations and what the ramifications will be - we really should be ashamed of our species as we are the ONLY ones that can rectify it.  Those in power choose not to..but that's another subject.....

Mike

[orage]

Did anyone see the documentery on ABC the other night about lightning. In it they talked about a city's influence in creating storms. As cities grow larger and spread out further, they collect more heat and have more and more of an effect on storm development. The example they used was Chicago which is becoming a hotspot for storms as it grows bigger and bigger.

[Mike]

Unfortunately I missed the ABC program of that - lots of folk have mentioned it to me.  Perhaps I'll ring the ABC here and get them to replay it! Without a doubt cities create their own weather - why do large cities always have strong wind problems also you could ask? - well the answer is that the wind does not just flow horizontally through the guts of the city and around buildings, wind actually travels up the sides of skyscrapers and then down them at the same time (bit like microbursts but with buildings), of course the wind will be much stronger as it comes down and spreads out amongst the public on the ground. I watched a NatGeo doco re this in Chicago, New York and Los Angeles where they studied this and it was very interesting to see just how the buildings actually help generate much stronger winds around the city just because the wind is being channeled between all types of structures - a bit like a water in a stream being pushed toward a larger river system, with time and with distance the water runs faster because of other forces pushing it along - much like with air, you can't see it but you can feel the effects of the forces altering it!

Mike