Saturday, April 14, 2007
Red River "RISING"!
The "seasonal thaw" in Manitoba was well underway when we her "blasted" by Arctic air for a couple of weeks, and temperatures "dipped" to unseasonable values. -20*C at night was not unusual in our area. Combine the temperatures with a turbulent, flowing, partially-open river, and "Frazil Ice" formed, causing the flow of the river to be impeded, and the "Red" started to "rise". She "spilled" her banks around Selkirk, flooding riverfront properties, the "Park", and the Selkirk Marine Museum, home to some tremendous Lake Winnipeg "nautical" history.
"Frazil Ice" forms when the water surface begins to lose heat at a very quick rate, the water becomes supercooled. Turbulence, caused by strong winds or flow from a river, will mix the supercooled water throughout its entire depth. The supercooled water will already be encouraging the formation of small ice crystals (frazil ice) and the crystals get taken to the bottom of the water body. Ice generally floats, but due to frazil ice’s ineffective buoyancy, it can be carried to the bottom very easily.
Through a process called secondary nucleation, the crystals quickly increase in number, and because of its supercooled surrounding, the crystals will continue to grow. Sometimes, the concentration is estimated to reach one million crystals per cubic meter.
As the crystals grow in number and size, the frazil ice will begin to adhere to objects in the water, especially if the objects themselves are at a temperature below water’s freezing point. The accumulation of frazil ice often causes flooding, and since frazil ice is found below the surface of water, it makes it very difficult for humans to detect its formation.
Usually what happens is the frazil ice accumulates on the upstream side of objects and sticks to them. The frazil ice accumulates as more gets deposited. The growth will extend upstream and increase in width until the point where the frazil ice accumulations bridge together and block the water. As more and more water flows against this block, the pressure on the upstream side increases and causes a differential pressure. This will cause the growth of the bridge to extend downstream. Once this happens, flooding and damage is likely unless otherwise prevented or controlled. This was the case in Selkirk at the bridge and other locations on the river, let's see the results.
"Ice Jam"!
Starting to "flow" again in the center of the river........
A "displaced" Channel Catfish..........
"Steve, quick, throw me back!"
The Sekirk Marine Museum "flooded", and then "froze"!
The famous Lake Winnipeg freighter "Keenora"......
The road into the Park becomes "submerged"..........
25 km/h, please.
The "Harbourmaster's office" was slightly "cool and wet" during my visit.........
The river was "encroaching" on Selkirk Air's Floatbase..........
Warmer temps have arrived recently, and the flood threat should diminish............
Today the "last word" of my Post goes to the "aircraft in the infield" at Selkirk Air, all safe and sound.......
"Adios"!
"Frazil Ice" forms when the water surface begins to lose heat at a very quick rate, the water becomes supercooled. Turbulence, caused by strong winds or flow from a river, will mix the supercooled water throughout its entire depth. The supercooled water will already be encouraging the formation of small ice crystals (frazil ice) and the crystals get taken to the bottom of the water body. Ice generally floats, but due to frazil ice’s ineffective buoyancy, it can be carried to the bottom very easily.
Through a process called secondary nucleation, the crystals quickly increase in number, and because of its supercooled surrounding, the crystals will continue to grow. Sometimes, the concentration is estimated to reach one million crystals per cubic meter.
As the crystals grow in number and size, the frazil ice will begin to adhere to objects in the water, especially if the objects themselves are at a temperature below water’s freezing point. The accumulation of frazil ice often causes flooding, and since frazil ice is found below the surface of water, it makes it very difficult for humans to detect its formation.
Usually what happens is the frazil ice accumulates on the upstream side of objects and sticks to them. The frazil ice accumulates as more gets deposited. The growth will extend upstream and increase in width until the point where the frazil ice accumulations bridge together and block the water. As more and more water flows against this block, the pressure on the upstream side increases and causes a differential pressure. This will cause the growth of the bridge to extend downstream. Once this happens, flooding and damage is likely unless otherwise prevented or controlled. This was the case in Selkirk at the bridge and other locations on the river, let's see the results.
"Ice Jam"!
Starting to "flow" again in the center of the river........
A "displaced" Channel Catfish..........
"Steve, quick, throw me back!"
The Sekirk Marine Museum "flooded", and then "froze"!
The famous Lake Winnipeg freighter "Keenora"......
The road into the Park becomes "submerged"..........
25 km/h, please.
The "Harbourmaster's office" was slightly "cool and wet" during my visit.........
The river was "encroaching" on Selkirk Air's Floatbase..........
Warmer temps have arrived recently, and the flood threat should diminish............
Today the "last word" of my Post goes to the "aircraft in the infield" at Selkirk Air, all safe and sound.......
"Adios"!
