Hi Mike, Awesome. Very nicely brought together.
************************************************************************** Loved the bit about the stunted poor excuses for trees I immediately flashed on Henri de Toulouse- Lautrec, one of the masters of the French Post- Impressionist school of painting who was also a bit that way (although not a tree). ************************************************************************* Waffling on, you are no doubt familiar with the Mallee Scrub . Unknown to most of the world, Mallee roots are the finest/ best heat output, wood fuel known to man. However I can assure you that they are a bit gnarly, and do not split like plantation grown pine. Gary From: aus-soaring-boun...@lists.internode.on.net [mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of Mike Borgelt Sent: Monday, 9 June 2014 7:29 PM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] Cloud proof fence You need to understand the geography and climate of SW W.A. The wheatbelt is the area in the SW where the rainfall is high enough to grow wheat. Check out any satellite photos of the area. The rabbit proof fence is the limit of that area pretty much. I had a pal in physics at UWA in the late 1960s who came from a farm just west of the fence. If they were lucky they got a crop 2 out of 5 years and then the bastard emus would be looking hungrily at it from the other side of the fence. So the fence location isn't exactly independent of the surface vegetation/rainfall characteristics. The rain is mostly in winter apart from the odd summer thunderstorm and comes from the showers following passage of cold fronts. Much of the rain falls on the coastal plain and Darling range (what there is of it - Perth is built on a coastal desert) and what is left goes to the wheatbelt. After the harvest in December the wheatbelt is nearly bone dry. Great outlanding country - tell me about it. Your biggest problem, if you didn't figure out where the fences/roads/houses were while still airborne is figuring out where to walk to after landing. If you fly there in summer you'll get good at flying in blue thermals except for the odd spectacular trough day which will have very high based cu and high convection. I've been to 16500 feet in blue thermals there. Much like South Australia but without a large river for irrigation fed by the Great Divide. The dry ground and only a little bit of dry stubble left means there sure as heck isn't a lot of evaporation (latent heat flux) as there isn't any water in the vegetation. In the scrub the stunted poor excuses for trees will however still evapo-transpire so in summer there will be more latent heat flux there. In August the rains are still happening in the crop growing areas with higher rainfall so that's where the latent heat flux is greater than in the scrub. Nothing all that surprising in that paper. What isn't obvious is the salinity problem. Lots of salt lakes and salt coming to the surface as a result of tree clearing. This has been addressed since the mid 1970s with replanting and other mitigation methods. Mike At 06:49 PM 9/06/2014, you wrote: Thanks Robert, Just to clarify for me. "The latent heat flux is the movement of heat energy from the surface to altitude associated with the evaporation of water at the surface and its condensation at altitude in clouds."  I take it that, Latent heat flux is one of the effects which generates thermals. The other is sensible heat ie ground gets hot, transfers heat to near surface air by conduction. Air then rises (convection). Do you have any thoughts on why the natural vegetation (we used to call it scrub) has a strong bias to Latent Heat Flux in December but not in August? On Sun, Jun 8, 2014 at 11:17 AM, Robert Hart <crispin...@gmail.com> wrote: On 08-Jun-14 08:44, Peter Champness wrote: That seems right. They should have asked glider pilots. I note that the paper shows that the latent heat flux is strongly skewed to the native vegetation areas in Dec (soaring season). In August it is the other way, higher over the agricultural areas. I assume latent heat flux means avapoeration. Latent heat is the heat absorbed or released during a phase change (ie solid/liquid/gas phases). In water, there is very significant latent heat involved in evaporating water which is then released when the water vapour recondenses to liquid water (droplets) in clouds. The latent heat flux is the movement of heat energy from the surface to altitude associated with the evaporation of water at the surface and its condensation at altitude in clouds. As flatland glider pilots, we ride this flux in the form of thermals generated by a number of effects. -- Note: I am changing my email address - please only use my gmail address from now on! Robert Hart                          crispin...@gmail.com +61 438 385 533 _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978 www.borgeltinstruments.com <http://www.borgeltinstruments.com/> tel: 07 4635 5784 overseas: int+61-7-4635 5784 mob: 042835 5784 : int+61-42835 5784 P O Box 4607, Toowoomba East, QLD 4350, Australia
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