Re: Re:OT:wind chill
From: Kenneth Walker <kenww@pacbell.net>
I would agree with your assement. The only way wind
can cool an object below the air temperature is by
rapid evaporation; evaporation should be slow in plants
in the winter. But I would add that if a plant's sap is frozen,
it cannot replenish water that sublimates from its exposed
parts. That may contribute to winter windburn in trees and shrubs.
Ken Walker; Zone 9, but born on the cold side of Zone 4
Dan & Marilyn Mason wrote:
> It is my theory that wind chills are dangerous for people because
> the cold wind is good at quickly removing heat from the exposed
> object. An exposed plant quickly cools to the temperature of the
> air, but this is not dangerous to the plant if it is hardy for
> that area. Once the plant has cooled to the air temperature the
> wind cannot remove more heat from the plant.
>
> But the cold wind is very dry. It is quite capable of removing
> moisture from the exposed parts of plants. Prolonged extreme
> cold and wind can have a drying effect on plants. This probably
> would have more damaging effects to semi-hardy shrubs than
> iris. But iris growing in a wind exposed site that did not have
> mulch or snow and went into the winter with dry conditions
> could be further dried by extended periods of low windchills.
>
> This is just my theory. My iris have always been snow-covered in
> the coldest weather. I have lost very few low growing plants from
> winter weather thanks to our continuous snowcover in winters. I've
> seen more damage on semi-hardy shrubs, blackberries, black
> raspberries, grapes, apples, roses, etc. On semi-hardy deciduous
> plants the parts not receiving protection from the snow die back
> after cold winter weather.
>
> Dan Mason zone 3, NW Ontario
> dmason@rainyriver.lakeheadu.ca
>
> (Where if our kids have appointments 60 miles away this time of
> year, it will almost always occur on one of the colder days of the
> winter.)
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