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#1
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Australian bush-fire
I was viewing the BOM (Bureau of Meteorology) weather radar of Victoria
(17:00 07/02/2009) despite the fact that locals assure me that there was no rain at the time over eastern Victoria a number radar returns indicated very heavy rain at a number of the bush-fire sites. It appears that the radar was detecting the smoke. I was under the believe that weather/rain radars gave returns from rain droplets and that smoke should give little or no return. Any thoughts! http://mirror.bom.gov.au/products/IDR023.loop.shtml -- Peter VK6YSF http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm |
#2
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Australian bush-fire
On Feb 7, 7:18*am, "Peter" wrote:
I was viewing the BOM (Bureau of Meteorology) weather radar of Victoria (17:00 07/02/2009) despite the fact that locals assure me that there was no rain at the time over eastern Victoria a number radar returns indicated very heavy rain at a number of the bush-fire sites. It appears that the radar was detecting the smoke. I was under the believe that weather/rain radars gave returns from rain droplets and that smoke should give little or no return. Any thoughts! http://mirror.bom.gov.au/products/IDR023.loop.shtml -- Peter *VK6YSF http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm Weather radars declare a weather target based the amount of signal recieved back or reflectivity of the target. The greater the reflectivity the heavier the weather. Typically a series of 6 thresholds are set up with the minimum threshold indicating the minimum level of precipitation the radar will report, under normal conditions smoke will reflect less signal than is required to meet the first threshold. Raging brush or forest fires are not normal conditions as they put a huge amount of particulate matter and moisture into the air. Otherwise there is not normally anything special about weather radars that would allow it to tell the difference between weather and smoke. Then again new technology is always coming along. Most modern radars produce a digital image of the weather in memory . This image is the processed by computer to declare targets. If there is a difference between the signature of weather and that of smoke it may be possible that software could or has been be developed to tell the difference, if this is the case I am not aware of it.. Jimmie |
#3
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Australian bush-fire
On Feb 7, 7:18*am, "Peter" wrote:
I was viewing the BOM (Bureau of Meteorology) weather radar of Victoria (17:00 07/02/2009) despite the fact that locals assure me that there was no rain at the time over eastern Victoria a number radar returns indicated very heavy rain at a number of the bush-fire sites. It appears that the radar was detecting the smoke. I was under the believe that weather/rain radars gave returns from rain droplets and that smoke should give little or no return. Any thoughts! http://mirror.bom.gov.au/products/IDR023.loop.shtml -- Peter *VK6YSF http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm who cares brainless bluster |
#4
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Australian bush-fire
"Peter" wrote in message . au... I was viewing the BOM (Bureau of Meteorology) weather radar of Victoria (17:00 07/02/2009) despite the fact that locals assure me that there was no rain at the time over eastern Victoria a number radar returns indicated very heavy rain at a number of the bush-fire sites. It appears that the radar was detecting the smoke. I was under the believe that weather/rain radars gave returns from rain droplets and that smoke should give little or no return. Any thoughts! http://mirror.bom.gov.au/products/IDR023.loop.shtml -- Peter VK6YSF http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm Probably not from the smoke. The interface between the column of hot air and cooler air probably caused the reflection. Cheers, John |
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