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Official Vs. Actual Temperatures

Posted by saood Saudi - 10b (My Page) on
Mon, Oct 14, 13 at 6:38

I never knew the officially reported temperatures would be so different from the actual reading under direct sunlight. I bought an outdoor thermometer to measure the temps that my vegetable plants are facing. These days the highs as reported by the weather channels is 95F. Whereas my thermometer shows me 110F.

I came to know that the official temps are recorded under shade i.e. they are air temperatures....

Now this raises a question. When they say that the 85-86F is the temperatures beyond which a tomato will not fruit (or its productivity will be impaired), are we talking of the air temperature or the temperature that the plant is facing. With 6-8 hours under direct sunlight, the direct sunlight temperatures seem more relevant. Is it so. Or is it that when they speak of 86F for tomato they are actually speaking of the air temp. Can some expert clarify this?

Here is a link that might be useful: Why official temperatures are recorded in the shade?


Follow-Up Postings:

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RE: Official Vs. Actual Temperatures

I am by no means an expert. I can not answer your question definitively but I did keep careful track of temperature and productivity this year. I kept my thermometer protected from the sun and wind, but I only used the one thermometer. I don't know what the corresponding “in direct sunlight” temperatures were. I grew ten varieties seven of which are widely thought of as good heat setting types. The first variety to shut down quit setting fruit when the air temperature was regularly around 88 to 90 degrees, and all but one had shut down by the time the air temperature was regularly between 96 and 98 degrees. Juliet finally quit at about 99 degrees in the shade. Next year I plan to try Legend, a parthinocarpic variety that will set fruit without pollination to avoid heats' effect on pollen.

Mike


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RE: Official Vs. Actual Temperatures

All temperatures are given as air temps ..


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