A Small Rant On Cold Famine Hype

Over on WUWT, I left a rather long comment on one thread. I’m reproducing it here so I can have the links available in the future. This first quote is from the article at the top of that posting.

I would also add this link:

http://www.hort.purdue.edu/newcrop/FamineFoods/ff_home.html

It has an extensive list of the various plants we can eat in “hard times” if we really need to do so. From the leaves of those green beans that we presently disc under or consign to the compost heap, but eaten in Africa as a ‘pot herb’, to Kudzu that’s all over The South (and forbidden to be brought into California since it grows so well) and more. Heck, even rose hips are edible, as are a few dozen “ornamental” plants we grow just for looks. But for now, back to the original quote from that WUWT article:

“Moreover, a 2-degree drop in average global temperatures would shrink growing seasons, cropland and wildlife habitats.”

A modest quibble. It is more “move” seasons and habitats than “shrink”. Much of it can be adapted to via swapping crops. This is a large and complex topic (basically most of what farmers do) so only a couple of short examples.

1) Phoenix Arizona. The “down season” for gardens there is mid summer. It’s hard to grow things in July, August, and sometimes September. So what to do? They grow heat adapted varieties, or plant heat sensitive things in winter, spring, and fall. Now, as things cool, summer “hard time” becomes “good time”. I’ve pointed this out going the other way: That growing crops is not heat limited until a place is as warm as Phoenix Arizona. I.e. about 120 F+ or about 50 C+. In this case of cooling, Phoenix in summer becomes available for growing crops other than those particularly suited to a hot desert.

2) Iowa. At present, it grows a LOT of “field corn”. Field corn is not eaten by people (other than a few hardy souls …) and is a tough hard grain mostly fed to chickens, pigs, etc. It can easily take 100 to 120 days to mature and it really likes the heat. If the summers get cooler, there are cooler crops that can be grown. Go more north, you get more wheat. Above that, rye. Eventually you run into barley and buckwheat. BTW, you can also grow barley in Arizona… just adjust your season. Think on that for a minute. Barley is grown in Alaska, and Arizona… Think you can get it to grow in a 2 C different average?…

http://ethnoleaflets.com/leaflets/barley.htm

Barley is very adaptable to various environments. In fact, it is the most adaptable of the cereals. Barley is an annual grass that has two growing seasons, winter and spring. It does best in the spring in a temperate zone with a 90 day growing season, it can also be found growing in sub-arctic regions, like in Alaska or in Norway, with very short growing seasons . Barley also has a very good resistance to dry heat compared to other small grains. This feature allows it to grow near desert areas such as North Africa.

You don’t need 90 days. There are some very short season barleys. Historically, it was far more common than corn, but over the last century, corn has taken dominance. Why?

http://www.agmrc.org/commodities__products/grains__oilseeds/barley-profile/

U.S. producers harvested 2.24 million acres of barley in 2011 with an average yield of 69.6 bushels/acre. Total production was 155.8 million bushels, which was the smallest annual production level since 1936 and approximately one-half of the 2000 production level. Much of this decline can be attributed to increases in corn production in northern climates that have historically produced barley. The advent of shorter-season corn varieties, coupled with record corn prices, has caused production substitutions away from barley towards corn.

Because of “short season” varieties of corn. Unlike the original Indian Corn that was typically a 75 to 100 day corn even for eating as roasting ears, I have in my seed archive a 45 day sweet corn. Yes, it’s a bit of sellers puff in that where I am it takes more like 50 to 55 days in reality, but still, it’s a whole lot faster than it was.

http://moongrow.com/vegetable_planting_guide/barley.html

Grow and plant barley as you would wheat. Some varieties are spring planted and some are fall planted. Barley ripens sooner than wheat; spring-planted barley ripens in 60 to 70 days, fall-planted barley about 60 days after spring growth begins.

So as “growing season” shortens from 120 days ( or in some places even up to 270 days ) we can substitute other shorter season crops. Such as Barley. (This glosses over an important point: In many cases we have gone to ‘double cropping’ as the season length of the main crop has shortened… so barley is now often grow in addition to corn. So for this double cropping to continue, we would need shorter crop cycles, as we have developed for many crops over the years…)

We don’t grow barley all the time because we want corn more, for a variety of reasons from having the corn drilling and harvesting equipment to being familiar with it to liking the sound of “corn fed beef”… but barley is fine for cattle feed too and we can eat it (or drink it ;-) if needed.

So is that IT? Just barley? Well, no. Ever hear of “buckwheat cakes”? Yeah, we don’t eat them as much now, as we have SO much excess wheat it is silly. But Soba noodles in Asian cooking and buckwheat pancakes are still pretty good.

http://www.hort.cornell.edu/bjorkman/lab/buck/guide/whygrow.php

Why Grow Buckwheat?

Buckwheat is a short-season cash crop with properties that can make it fit specific situations on your farm. While it is unlikely to be your main crop, it can be a worthwhile part of your overall farm plan.

Reasons to grow buckwheat

Fits into rotations at a time when fields might otherwise be idle.
Can be grown as a catch crop where another crop failed.
The check arrives within 90 days of sowing.
Inexpensive to grow because it requires no pesticides and little fertilizer.
Can be grown with equipment available on most farms.
Requires little attention during the growing season.
Mellows the soil and suppresses most weeds.
Easily raised organically, at a premium price.

Notice, in particular, that line about the check? From seed in the ground to delivered to the customer for payment in under 90 days. It really likes about 70 F as ideal. So until Iowa has summer temperatures under 70 F and a growing season less than 2 1/2 to 3 months, we can grow grains there.

And don’t even get me started on kale… Siberian Kale has been harvested from under light snow… Historically, Amish farmers (my ancestors, BTW) grew various beets and turnips for cows. Why? They grow in the cold reasonably well, and keep very well in very cold conditions. Sadly, many kinds of “fodder beets” are being lost as varieties since we now just grow warm season feeds like corn, soy, and alfalfa hay… but some folks have kept a few of the varieties around.

http://sustainableseedco.com/heirloom-vegetable-seeds/a-ca/beet-heirloom-seeds/red-mammoth-mangel-beet-seeds.html

Fodder beets have been around since the 1400s if not earlier. These beets were prized as nutritious animal feed that was easy to store. Fodder beets are hardy, adaptable and palatable. They are ideal for planting in late summer for use as a winter and spring crop.

Red Mammoth Mangel Beets produce an incredible mass of edible beet leaves and a large root up to 20# or more in size! These beets prefer deeply tilled, free draining, sandy soil to achieve full size. Simply allow your animals to graze on the tops, cut the tops for feeding or harvest the root.

Surprising how juicy and sweet these giant beets are!

1940 Oscar H. Will Pure Seed Book says…
“The heaviest yielder and most popular of all Mangels the light red roots are pinkish fleshed and grow well out of the ground. Yields run as high as fifty tons to the acre.”

This is a sure way to put away enough food for your animals as they face the cold winter. Leave them in the ground and harvest as needed. Unless you are covered with snow, then I suggest you root cellar them.

So there are many “old ways” of getting through a very long winter with a short season for growing things that are only expecting mild warmth. You can harvest these things at about 60 days, but 90 days gives a better yield for cows (a bit fibrous for people then).

It’s a long list of such things…

But the basic idea is really pretty simple: We grow what we grow now not because it is the best product, or the fastest, or produces the most, or is the most cold tolerant. Mostly we do this because it is what we want. If things got tough, we could rapidly want something else that was faster… or more cold tolerant. Instead of “corn puffs” for breakfast, we could go back to buckwheat cakes… Until Iowa is under 70 F in August…

So, IMHO, there isn’t nearly as much disaster looming on the crop front as this paints. Yes, it would be a big problem to lose the northern bands of Canada and Siberia. Yet we would be gaining growing time in Arizona and Mexico.

There is a real problem with the change, but it isn’t the loss of crops to cold. It is the loss of crops to rain and wind.

During the LIA, much tall wheat was lost to “blow down” or “lodging” as the gusty strong winds blew it over. Newer short stem varieties can help with that, but not stop it. Similarly, it does no good to say “we have a shortened growing season from 180 days to 90 days, so go plant barley” if the fields are full of mud. Excess rains were a big problem for crop production in the LIA. So look more at the winds and rains (and mud). That’s where there will be a problem.

For simple cold, crops will all just move southward a couple of hundred miles in terms of who grows what where (with some far north corn moving to south Texas where they grow sorghum and millet in the heat…) and for shorter growing season, varieties will shift to short season types that match the available time. In severe cases, folks will swap to the traditional “catch crops” like buckwheat.

And none of this is even getting close to “exotic” methods. California provides most of the table vegetables for the USA (and fruits and nuts for the USA and for export). Anyone could replace California in that role at slightly higher prices using greenhouses. California uses a lot of them already. (You get about a 5 x to 10 x increase in yield per acre, but with higher costs. For things like lettuce, the increased quality means folks will pay up for it – so many specialty lettuces are now hydroponic greenhouse grown. Look for butter lettuce in plastic containers with a clear root lump still attached as an example.) Greenhouse tomatoes are taking over the world, and in Saudi Arabia they grow a lot of “truck vegetables” in greenhouses using desalinized water. All you really need is sand and ocean to grow loads of vegetables at reasonable rates – just not quite as cheaply as in Mexico or California dirt in most years. See: http://seawatergreenhouse.com/ for example). So in a real “aw shit” you would find Arizona and The Outback of Australia and The Sahara and… all putting in pipelines to the ocean and building greenhouses. Yes, costly. Your dinner salad might cost you a $1 more… depending on how far you are from an ocean and desert….

Who suffers from that? The cows and chickens and pigs who wanted Cow Chow and Pig Chow made from heat loving corn and soybeans (which we grew in the first place because Iowa in August is more like 105 F than 70 F) and instead have to eat barley and buckwheat, or the ‘slash’ from our greenhouse vegetables instead. Then again, pigs and chickens like that rather a lot and cows are quite fond of beet tops…

We are up to our eyeballs in food in the USA and it just isn’t going to make a bit of difference to us. (Folks with dysfunctional governments, like just about every country in Africa and the Middle East other than Israel will have a very hard time of it as they get drought when things get cold and do not have the stability to do much more than basic ag and certainly will not be making greenhouses fast enough… they depend on the USA for wheat, corn and soy to far too high a degree, so they will suffer.)

https://chiefio.wordpress.com/2013/01/11/grains-and-why-food-will-stay-plentiful/
https://chiefio.wordpress.com/2013/05/04/knowing-beans-and-lentils-and-peas-and/
https://chiefio.wordpress.com/2009/05/08/there-is-no-shortage-of-stuff/

(BTW, it isn’t just grains… beans too. Tepary beans grow in the desert heat, peas and favas in cold and wet. Just changing which to grow is enough for everywhere but the very edge, and what is lost at the very cold edge tends to be added at the too hot edge…)

Yes, a long rant. But Dad grew up on a farm, and I grew up in farm country, and I really do wish folks would talk to farmers before saying that a couple of degree change is going to end farming and food supply… Cattle can graze from scrub desert to frozen Canadian north, too, so it isn’t just grains and beans…

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
This entry was posted in Emergency Preparation and Risks, Food, Plants - Seeds - Gardening and tagged , , , , , . Bookmark the permalink.

23 Responses to A Small Rant On Cold Famine Hype

  1. M Simon says:

    Nice commentary. I left this reply:

    Agriculture is such a science that they can schedule harvesting for optimum use of agricultural machinery. You can read about it in a book called “Operations Research for Management” by Hopkins. Published in 1954. They discuss (among other things) a climatic slide rule, designed to optimize the growing season. It explains why your 45 day corn takes 50 or 55 days. Time of planting (day, month).

  2. alexjc38 says:

    A fine counterblast to the perennial doom merchants, like the Ehrlichs or Lester Brown – greatly enjoyed this post.

  3. M Simon says:

    This is the chapter: http://people.fas.harvard.edu/~eebutler/Homepage/2012-2013_files/Thornthwaite_OR%20in%20Ag_1953.pdf

    Operations Research in Agriculture
    Author(s): C. W. Thornthwaite
    Source: Journal of the Operations Research Society of America,
    Vol. 1, No. 2 (Feb., 1953), pp.33-38
    http://www.jstor.org/discover/10.2307/166714?uid=3739656&uid=2&uid=4&uid=3739256&sid=21106781584333

  4. M Simon says:

    sabretoothed says:
    11 May 2015 at 6:52 am

    The guy you linked to is a grade A idiot. Other than getting “it’s the sun” right he goes on with this kind of colossal Communist stupidity. Yeah. It is a conspiracy all right. Just not the one he imagines.

    If they were really concerned about climate change and NOT about profit, they would simply start looking to develop free energy devices, they would release patents on devices that have been confiscated for being too energy efficient, cars would run on hydrogen, and solar panels would be everywhere.

    ================

    Free energy? If only.

  5. sabretoothed says:

    Yeah I know there is BS on it, but its has some good planet links which were actually real :P

    Also interesting about the earthquake in Nepal and Upper atmosphere http://www.nasa.gov/jpl/gps-data-show-how-nepal-quake-disturbed-earth-s-upper-atmosphere

  6. tom0mason says:

    Very nicely said EM,
    Of course we never survived the Maunder or Dalton minimums, we were all wiped out during the Medieval Optimum — well hopefully it was the only the Left-wing Marxists types due to their lack of common sense. :)
    Temperatures rise or fall and the survivors are the ones that adapt — darn lefties just want everything to be unchanging, static, and can never see beyond their stasis view, as if now was somehow near perfect. Sad really, no experience beyond their office desks, no practical experiences to draw on, and such limited imaginations. Progress to the lefty is diminution of human talent, containing and reducing individual and common knowledge, limiting outcomes, the necessary lowering of all individual worth and expectations — except for the elite lefty. Progress to me is the flourishing of practical talent and skill, the expansion of individual and common knowledge, and the rightful raising of individual expectations, rank, and worth.

    My favorite standby food is oats. This hardy cereal from temperate regions is relatively easy to grow, easy to store, and versatile. Wonderful oatcakes, oat breads, biscuits, and cookies, and I’ve real skill making porridge. :) It is also excellent animal fodder and oat straw makes good bedding material.

  7. omanuel says:

    Thanks, E.M. Smith, for posting information that will be more valuable that gold if the Sun continues to go dormant.

  8. Ian W says:

    As you state the problem in 1315 and ‘The Great Famine” (http://en.wikipedia.org/wiki/Great_Famine_of_1315%E2%80%9317) was the continual rain. From an account of the time:
    Seven weeks after Easter in AD 1315, sheets ol’ rain spread across a sodden Europe, turning freshly plowed fields into lakes and quagmires. The deluge continued through June and July, and then August and September. Hay lay flat in the fields; wheat and barley rotted unharvesred.”

    It was warm enough but the weather was too wet. The same happened a couple of years ago in South West England with rains ruining the harvest.

  9. omanuel says:

    As “cosmic rays” traverse air, they produce ion-pairs that serve as nucleation sites for water vapor to condense into water droplets, i.e., rain.

    The Sun’s pulsar core also produces “cosmic rays,” but most are absorbed and re-emitted as longer wavelength radiation from the H,He-rich photosphere.

    When solar activity is low, the flux of “cosmic rays” striking the Earth’s upper atmosphere is high.

    At present, the mean flux of “cosmic rays” is the highest since 1958:

    http://notrickszone.com/2015/05/10/mean-cosmic-radiation-over-past-8-years-highest-since-1958-current-solar-cycle-weakest-in-almost-two-centuries/#sthash.IwgSRytc.djMpP07y.dpbs

  10. punmaster52 says:

    Fodder beets have been around since the 1400s . . .

    Just imagine if these fields were close to historical sites or museums, and there were good hotels and restaurants close by. Someone could write an interesting travel guide.

    @omanuel:

    If the sun continues to go dormant none of this information will matter at all, will it? ;-)

  11. omanuel says:

    @punmaster

    You are right ! Nobody will be around to count the bodies of dead dogmatic scientists and Catholics.

  12. E.M.Smith says:

    @OManuel:

    I know, it’s because the Pope has hopped onto the AGW bandwagon, so that makes him “fair game” in the idiots parade… but please, can we avoid slander toward ALL Catholics? I”m married to one… Dad was one. Mom became one. (So far, I’ve dodged the bullet ;-) though I did go to mass with the spouse last Sunday…)

    I do like to keep the place modestly free of insult to large groups of humanity (unless, of course, they have shown themselves deserving of it, such as the Radical Islam Nutballs, and unlike the various decent Muslims with whom I have worked.) So if an entire group, or subgroup, is to be insulted, make sure you have strong evidence they did, in fact, do something to deserve it.

    Per Cosmic Rays:

    I suspect we’re going to get a very good test of the cosmic rays to clouds hypothesis…

    @Punmaster52:

    The yields on those things can be amazing. 50 TONS per acre. So my 1/8 acre lot could grow about 6 TONS of them. Or in my 1/16 acre that isn’t under house and stuff, about 3 TONS. Now 6000 lbs (short tons assumed) means about 3000 lbs / person (only 2 of us now) and that’s about 8 lbs / day every day of the year. WAY more than could ever be consumed by a mere human… (Not to mention you would be very tired of beets after the first day…)

    I ought to find out if any of the reenactor museums have “period correct” use of fodder beets. The harvest of these things is a sight. Large horse drawn wagon filled to the top with 20+ lb beets, some greens still attached, men tossing them on with pitchforks, horse sometimes snacking on a bit ‘o greens as he passes… (Don’t remember where I saw that, or when… long long ago…)

    It would make a hell of a statement about “yield” and what farming meant – cooperation of man and horse and cattle, each helping the other.

    @Ian W:

    You might like:

    https://chiefio.wordpress.com/2012/08/17/great-famine-of-1315-vs-the-sun/

    If past is prologue, Europe better start planting a whole lot more potatoes… (they handle the wind and rain better…)

    @TomOMason:

    Dang it. I forgot to mention oats… it can germinate down at 34 to 37 F (!) which is just astounding. As long as the soil isn’t frozen, you can grow oats. Here in California, it grows in the dead of winter, then turns brown in spring dryness ( there are already dry yellow stands of “wild oats” along the roads here, even the freeway in the middle of Silicon Valley). I have a jar of oat seeds just for the purpose of an “easy winter grain” crop…

    But thanks for the endorsement anyway ;-)

    @Sabertoothed:

    And is the solar system now showing signs of cooling?…

    @M. Simon:

    Well, now that you mention it, one of my required courses at the Ag College I attended was “Operations Research”. Guess what we studied a lot… yeah, crops…

    Did I mention it was an Ag school?… (We also did the obligatory steel and manufacturing cases too…)

    One of the interesting bits we looked at was how it no longer made sense to own your own harvester unless it was a special case. For things like wheat, they start running whole herds of them down south as the most southern ripens, then just mow all the way to Canada as they follow the ripening line…

    @alexjc38:

    I’ve pondered writing a “counter point” book to the Gloom And Doom All Limits ALL The Time folks. Sort of a “No Limits To Growth” (counter to the “Limits To Growth” by Meadows et. al.).

    Think there would be a market for it? (He said, blatantly fishing for motivation ;-)

  13. M Simon says:

    For things like wheat, they start running whole herds of them down south as the most southern ripens, then just mow all the way to Canada as they follow the ripening line…

    That means a considerable amount of co-ordination when it comes to planting.

  14. craigm350 says:

    Don’t have to quite as far back as 1315 in Blighty for bad weather –

    Had an air frost in mid August last year. Could do without any any more of them.

  15. craigm350 says:

    Reblogged this on the WeatherAction News Blog and commented:
    Looking for ideas for what to plant if we don’t get the promised Mediterranean summers? It’s not all doom and gloom.

  16. Larry Ledwick says:

    In Colorado sugar beets were a major cash crop for about 100 years, and the whole area north of Denver along the Platte river was prime sugar beet country.

    All that ended in the 1970’s as sugar cane and near slave labor harvest killed the economics of beet sugar. It caused a lot of dislocation and lots of jobs lost in the area as one plant after another shut down. We could easily go back to beets if need be around here.

  17. I’m pretty sure that historically there was more variation in the maturity time for corn.Consider this quote about the Lewis and Clarke expidition’s winter stay in what is now North Dakota:
    “It was Mandan corn that got the expedition through the winter. Had the Mandans not been there, or had they had no corn to spare, or had they been hostile, the Lewis and Clark Expedition might not have survived its first winter.”
    Ambrose, Stephen E. (2013-04-23). Undaunted Courage: Meriwether Lewis, Thomas Jefferson and the Opening of the American West

    I lived in both N. Dakota and Iowa, and you don’t have near the heat and length of growing season in ND.

    There may be some of the short season varieties still around, but hardly in use, because the yield is better with the longer growing varieties.

  18. omanuel says:

    @ E.M. Smith I apologize for using the term “dogmatic scientists and Catholics.” It probably was an unconscious response to the Pope’s recent endorsement of AGW, but not intentional.

  19. Paul Hanlon says:

    Actually Chiefio, I think you’d be the perfect candidate for writing a book called No Limits to Growth.

  20. E.M.Smith says:

    @Paul Hanlon:

    I consider myself motivated… some ;-)

    Thanks for the vote of confidence …

    @M. Simon:

    I think the coordination is automatically supplied by the temperature profiles… For example, winter wheat is planted in fall, then overwinters to wake up and finish growing in Spring. It wakes when warm enough, and that varies with latitude.

    Still, there is some variation and folks did have to work around that. Sometimes speeding up (longer days in the seat) and sometimes slowing down.

    Lately folks have gone to herbicide ‘burns’ to dry wheat on a schedule for precise harvest. Not keen on that as a load of herbicide ends up in the wheat.

    But yeah, coordinated. But mostly by weather and some by “everyone knows” when to do the planting, and some after talking to the harvester company to find out when they expect to be in your area…

    @James W. Radig:

    The “Indian Corn” varieties include many interesting types. Some can be used as sweet corn very quickly, then with full maturity for flour or grits. One has a tap root! (There are or were active efforts to get that gene into current corn types so as to have very drought hardy corn). I have a 45 day sweet corn (hybrid) in the seed freezer, and some 120+ day Indian Flint… so maturity can vary a lot.

    Yup, the further north the harder the growing conditions with shorter duration of warm, but with longer days in summer that partly makes up for it. Partly…

    @Larry Ledwick:

    When I was living near Sacramento in the ’70s there was active sugar beet growing for C&H Sugar. Don’t know if it is still there… but the C and H stood for California and Hawaii. One with beets, the other with cane. I’ve followed many a sugar beet truck loaded with monster beets… but not too closely as sometimes they fell off!

    The Mangle Beet isn’t quite like sugar beets. About 3-5% sugar IIRC where sugar beets are up around 20%. But great for cows… and sometimes people…

    As of now most all sugar beets used commercially are GMO ( or so I’d read a few years back )and the original sugar beets are one of the heirloom types most endangered as nobody really grew them but the industrial farmers. At least the fodder beets had the Amish…

    @Craigm350:

    Interesting that the quoted text says it was warmer in summers in the late 1700s on to 1810 than in the 1930s…. I’ve sometimes pointed out that Uppsala Sweden has a great long temperature record that shows the 1720 ish era as warm or warmer than today. I thought that was the only place it was noted. Now I see differently… Nice.

    “Air Frost”… had to look that one up. (Hey, I’m a native Californian… we barely had frost and then only in the dead of winter, certainly not enough to name different kinds ;-)
    http://weatherfaqs.org.uk/node/26

    So “air frost” is when it’s 0 C at the 1.5 M / 4 ft Stevenson Screen, and ground frost is when it is 0 C at ground level, while “grass frost” is 0 C in grass and plants, but not concrete, and there is even a thermometer set on a standard concrete bloke to record when pavement will frost… Golly folks in cold country have a lot of thermometers and kinds of frost! ;-)

    What’s the difference between a ground frost and an air frost?
    Submitted by uk.sci.weather on Wed, 17/01/2007 – 12:46pm.
    In day-to-day meteorology, the temperature of the lowest layer of the atmosphere is measured at a height of 1.25 m (about 4 feet) above local ground level. Usually, though not always, this is achieved by placing thermometers in a double-louvered screen with the bulbs of the thermometers, or the sensor heads (for distant reading thermometers), placed so that they cluster around the 1.25 m standard. The temperature so read is usually called ‘the air temperature’ and it is these values that appear, for example, in the World Cities reports in newspapers/teletext, or plotted on standard synoptic charts, and also it is at this level that the forecast temperatures seen on tv weather maps are based.

    When the temperature as measured in this way falls below 0.0 deg C, then an AIR FROST is recorded. For other purposes though, e.g. horticulture, road gritting operations etc., we need to know what the temperature is at the surface of the ground, and most weather stations set at least two thermometers to record these values: a grass minimum thermometer, set just above/in contact with short grass, and a concrete minimum thermometer, set so that its sensor/bulb is in contact with a concrete slab of standard dimensions/composition.

    When the temperature as measured by the thermometer set over grass falls below 0.0 deg C, then a GROUND FROST is recorded. (In spring and early summer, when the temperature is expected to produce a frost using the grass minimum thermometer, but not over other surfaces (due to thermal inertia of surfaces such as concrete, tarmac etc.), then the unofficial term ‘grass-frost’ may be heard in weather forecasts – this is to try and avoid panic by road, railway and airport operators as soon as they hear the word ‘frost’ but alert gardeners, growers etc., to the risk of damage).

    The difference between the two levels can be considerable: On still, clear nights, with air of a low humidity content, 5 degC or more is not uncommon.

    ‹ What’s the difference between a ‘shower’ and an ‘outbreak of rain’? up

    Wow, 5 C or more variation between ground, just above grass, and at Stevenson Screen height. And we’re supposed to panic over 0.5 C …

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