When does Black ice start? | GTAMotorcycle.com

When does Black ice start?

bigpoppa

bigpoppa

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As the temps get lower...and lower...i start thinking more and more about putting the bike away for the winter, at first i was thinking "ill do it in November" or "Ill do it when they start putting Salt on the roads"(Dont want that **** on the bike) ...

But now im thinking when does Black Ice start hitting the road? I read in theory it starts around 0 degrees, but could also occur a few degrees higher? Bridges also cool quicker than roads..
Around what temps do you start putting it away?
 
Be sure to be as alert for wet leaves and the like on roadways and in the middle of corners etc.
 
The theoretical possibility exists up to about 3 degrees C but it requires several factors for it to happen at that temperature: a road surface that is wet to begin with or which becomes wet through condensation (same process that forms dew/frost), a clear night sky (so heat from surfaces can radiate to the sky and not be replaced by heat radiated from other objects), no wind (so that heat from the warmer air doesn't transfer to the ground), and cooler temperatures for several days leading up to this (so that stored heat from the ground doesn't simply raise the surface temperature). Bridges will tend to freeze first because the surface doesn't have an enormous heat sink of stored energy underneath.

That's the science. The practical reality is that if the roads are dry and it's daytime and the air temp is above freezing, there's no ice (except possibly in spots shaded from the sun). If roads look wet and the temperature is near freezing, look out.

I normally don't winterize until roads have been salted and there's snow on the ground and staying there. Even if they brine the roads, if it rains afterward, it's gone. I rode last year on Christmas Eve, and the only reason I didn't ride on Christmas Day was that I had family obligations that day :)
 
Blackfin said:
Be sure to be as alert for wet leaves and the like on roadways and in the middle of corners etc.
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Yep. Right now, wet-leaves slime is the biggest concern. There's plenty of it on the back roads.

Once most of the leaves have fallen, if there are a few dry days, that stuff dries up and blows away.
 
Note Environment Canada's dew point. This is the temperature where the air can no longer hold moisture, so the moisture falls to the ground. If the road temperature is below the dew point and below zero, moisture from the air will fall to the ground and freeze, creating black ice.

For example, today's weather in Toronto has a dew point of 3.7C. If the outside road temperature was below zero, which is below today's dew point, we would have the conditions for black ice. Since today's temperature was 11C, above the dew point, it is warm enough for the air to retain its moisture. If the temperature was between 0 and 3.7 the air could not hold its moisture, dropping it to the ground, creating "dew".
 
I'm sure someone will correct me if I'm wrong.
It is most commonly seen in intersections due to the number of vehicles going over snow compressing the snow into ice.
You will then get a near freezing day which melts the ice somewhat, with it re-freezing again that night when it gets colder.
It strikes a chord in my memory that intersections seem to be the place that gets it the most often.
 
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I use the rule: is it 4 or above now, with a high above 10?
 
Brian P said:
The theoretical possibility exists up to about 3 degrees C but it requires several factors for it to happen at that temperature: a road surface that is wet to begin with or which becomes wet through condensation (same process that forms dew/frost), a clear night sky (so heat from surfaces can radiate to the sky and not be replaced by heat radiated from other objects), no wind (so that heat from the warmer air doesn't transfer to the ground), and cooler temperatures for several days leading up to this (so that stored heat from the ground doesn't simply raise the surface temperature). Bridges will tend to freeze first because the surface doesn't have an enormous heat sink of stored energy underneath.

That's the science. The practical reality is that if the roads are dry and it's daytime and the air temp is above freezing, there's no ice (except possibly in spots shaded from the sun). If roads look wet and the temperature is near freezing, look out.

I normally don't winterize until roads have been salted and there's snow on the ground and staying there. Even if they brine the roads, if it rains afterward, it's gone. I rode last year on Christmas Eve, and the only reason I didn't ride on Christmas Day was that I had family obligations that day :)
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Brian's explanation nails it. It is not something worth fretting about really unless you are riding in early morning or late at night into the colder months, and even then, only under a certain set of circumstances that can take days to develop. It's not something that's going to happen "every morning" or anything like that, and it's hardly a reason to put your bike away on an arbitrary date because of it. Like many others around here I rode all winter last year and had no issues, although this fall is looking and feeling much more traditional this year...I've not stopped yet.

As others have mentioned, fallen leaves, especially the wet slimy ones are a far bigger risk than worrying about black ice right now.
 
Cold pavement mostly from low-overnight temps is the biggest concern in the Fall months.
 
jc100 said:
Watch out under bridges where there's a permanent shadow.
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yup.. or rural east -west roads that have shadows from the trees [forest] that are close to the road... the low sun in the fall leaves the road in the shade. and that is when the local dew point goes higher than average ... become heavy dew on the road... then the overnight temps fall.. freezing it to black ice.. no sun or wind to melt it off.. it is more prevalent after a clear [no clouds] night..
there was black ice here this morning...
 
In the springtime, my rule of thumb is nighttime lows of 3 degrees or higher for about a week before the season starts (no standing snow preferably). Conversely, the nighttime lows need to be under 3 degrees for a similar period before the curtains close (keeping an eye on wet roads). Of course, I'm only commuting in Toronto during that part of the season, where the speeds only reach about 60kph, so I'm not demanding too much of the tires. Like riding in the rain, keep it smooth on the brakes and smooth on the throttle.
 
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