[Goldfinger]

Went to check over the plot yesterday, and in the poly some of the potatoes were looking 'sick'! 

Now, on Friday I was warned about a 'possible' frost, so I closed the doors.

Going in on Monday, it was strange to look at the potatoes, the ones nearest the doors were untouched, yet it was the ones nearer the middle that had been 'clipped' by something. 

Does it have to be an actual 'frost' to damage potatoes, or could all you need is a bit of really cold air??

The lowest I've seen here over the weekend was about 4-5 degrees, not near enough to frost temperatures.   

[Hampshire Hog]

Sorry goldfinger I think 4 degrees is enough to do damage even though it's not freezing.
Don't understand the location of the damage though would expect problem to be near door as you say. Only thought is with the doors shut could it have actually become too hot not too cold if you had a burst of sunshine

Cheers HH
 

[fatcat1955]

Probably what they call an "Air frost".

[Goldfinger]

Air frost? Even with the door closed?  :blink:

Here's a couple of photos to help....





The way the damage has been done, it's as if a 'gust' has swept in - down - up then out the other end, missing many other potatoes....

[mumofstig]

Could it have been cold condensation dripping onto those, cos it doesn't really look like frost damage to me 

[Goldfinger]

Could it have been cold condensation dripping onto those, cos it doesn't really look like frost damage to me 

Never thought of that..... 

At least the door's back open now, no risk of frosts. Just rain.   

[makedoandmend]

Folks,

I heard of a new type of frost - well new to me anyway!! It's called a 'Radiation Frost'. I always thought that bodies could only radiate heat energy ('positive energy') but apparently not.

There are a few hits on tinterweb about radiation frosts, which can kill off tender plants. So it doesn't seem to be anything to do with ground frosts or air frosts, but still not sure I can get to grips with the thermodynamics of radiated 'cold'.

Make do

[mumofstig]

New to you, rather than new!  it's just an explanation for one of the reasons that frost forms.

As a gardener, frost is frost and always relates to low temperatures, and the killing of tender plants......... there's no need for me to worry myself about the whys and wherefores 

[JayG]

As far as I know a radiation frost is the same thing as a ground frost - ie one which can occur on clear, still nights where the air temperature is above freezing but the ground radiates its warmth quickly enough for freezing air to sink and collect at ground level.

It won't happen above 0C on breezy nights because the cold air is dispersed, except in the most sheltered of frost pockets.

[Goldfinger]

Could be that too, 'frost pockets'. 

This windy weather we're having at the mo' is very deceiving, looking out the house window I think, 'Me tunnel!! It's going to get hammered!  '

Yet I go down, and it's a different world... Calm, peaceful and sheltered.  :happy:

So maybe where my 'poly is, it could be a 'pocket' for some kind of frost to form.

Guess I'll have to get a max/min thermometer for the tunnel.