I wish it would rain

[Odsox]

I have not the foggiest what is the difference between an air frost or a ground frost

How do you know the temperature was 3c ?
Obviously you have a thermometer somewhere above ground level, probably at eye level.
So on 1st of September you only had a GROUND frost ... cos there was frost on the grass but your thermometer said +3c
If your thermometer reads zero or below you are having an AIR frost as well as a ground frost.

[grahamhobbs]

Also was it a maximum and minimum thermometer, otherwise all you can say it was 3degC when you read it. For the ground to be 0degC in September surely the air temperature would have needed to fall below 0degC at some point to cool the soil down to 0degC.

[KathyLauren]

For the ground to be 0degC in September surely the air temperature would have needed to fall below 0degC at some point to cool the soil down to 0degC.

The ground seldom cools by contact with cooler air, except perhaps immediately after a cold front. More typically, the ground cools by radiation, and the air is cooled by contact with the colder ground. On a clear night, the ground will normally drop below freezing first. Only if it stays frozen for long enough will it cool the air above it below freezing too.

Same in reverse when it warms up: it is the ground, not the air, that absorbs solar radiation and warms up. The warm ground in turn warms the air.

[grahamhobbs]

Thanks KeithBC, that makes sense now

[Millymollymandy]

I have not the foggiest what is the difference between an air frost or a ground frost

How do you know the temperature was 3c ?
Obviously you have a thermometer somewhere above ground level, probably at eye level.
So on 1st of September you only had a GROUND frost ... cos there was frost on the grass but your thermometer said +3c
If your thermometer reads zero or below you are having an AIR frost as well as a ground frost.

I have a thermometer, min/max obviously!
You've just said the opposite of what you said before, that I couldn't have a ground frost if the ground was warm in the autumn, only an air frost. Ice on the grass/bird water is the only way I know when we have a frost cos I can't see frost in the air - it doesn't show!!!

[Odsox]

You've just said the opposite of what you said before,

No, I was just explaining your observation.

In early autumn the soil is still warm, so even if the air temperature drops to 2.9c as it did in Aberdeen, it doesn't follow that you will get a ground frost as it takes several cold days & nights to cool the ground enough, or a VERY cold night. Light dry sandy soil will cool quicker than wet heavy clay.
The same effect is even more obvious here by the gulf stream warmed sea, the temperatures inland can get down to -10c but the sea temperature very rarely drops below +11c. If that didn't happen we would get ice on the sea when air temperatures dropped below freezing.

[Millymollymandy]

But that doesn't explain how we get frosts here when it is warm in September. As I said it's much hotter here than Aberdeen - was just talking to a friend who lives there this morning and he says the daytime highs are 15 or 16 *shiver* whilst here they are 24 or so right now! So my soil being light and sandy is quite naturally miles warmer than a clay soil in Aberdeen, yet we can still get frost on the grass and on my birdbath (about thigh height) at about 3C.

Anyway it doesn't mattter, for now there is no frost! And back on topic I am watering all my flower beds again but not with tap water, just back and forth with a watering can as we still have a reasonable amount of stored rain water and I really don't want to use any more mains water as I must have used at least 100m3 this year. I did get the seep hose out for the peach tree though as the fruit is just starting to swell from large marble size, amazing how it grows so quickly in just the 3 weeks of September until they are ripe! (but only if I water that is)

[mamos]

Certainly got you wish today it is bucketing down here in cornwall

I have two of the windows out of the Airstream for repair and I was supposed to go rowing this morning but it has been canceled due to bad viability

The chickens are in the conservatory to keep out of the rain and the water buts are over flowing

Oh well looks like I will be doing my books today in stead

mamos

[Odsox]

No rain here yet although it's very overcast and the forecast is for about an inch this evening.
Rather windy too, but I don't mind that as the whole house today will be on the wind turbine.
Certainly autumnal.

[Millymollymandy]

Our rain coming tomorrow evening....... can't wait!

[Odsox]

Well I got my wish eventually.
It rained hard and blew a gale yesterday evening and there was just about an inch in my rain gauge this morning.
Problem is, it's a brilliantly sunny day this morning with temperatures of about 25c, which is a tad warm for here and likely to dry up all the moisture we had. Never satisfied eh ?
Not too worried though as more rain is forecast during the coming week.

[Millymollymandy]

25C!!! Does this mean you get your shorts out? Still waiting for rain here.

Went to Rennes this morning which hasn't had real rain since about February apart from one freak rainstorm where they got 33mm back in about May/june. It is full on autumn there with all the trees yellow and orange, leaves falling everywhere and even conkers on the ground. Really, really sad. We were so lucky to get those two big rainfalls here in August which has helped immensely, although it's rapidly drying out again.

[MKG]

At the moment here it's dry, if a little windy.

Today, I have a large delivery of building materials coming, and the delivery condition is kerbside only. It'll take me about three hours to move everything. The delivery time is between 12 and 4 - which means 4.

I know what's going to happen. Just as they pack up and leave, the heavens will open. I know it. I feel it in my water.

Mike

[Millymollymandy]

that's what usually happens when we have firewood delivered! Can't you get a tarp over it all and wait until it is dry (if it should rain)?

I hear distant rumblings here. Course that will happen when I go out to clean out the duck shed soon and on the rare occasions it does rain it's always when I have just blow dried my hair.

[Odsox]

25C!!! Does this mean you get your shorts out?

I would do but some people think I look silly wearing shorts over my long johns.
It's not so bad now, a nice cooling sea breeze has sprung up.