Michael Percy writes

Do a reality check with a rainfall map of earth. What you see, the rainfall
isosomethings in the range 0 to 20" closely capture the arid parts of earth
including the deserts. Don't ask me why it does, but it is a fact. You
can't get the same mileage from a transpiration rate map.

That's a rather huge range, to put it mildly, and puts parts of the UK
and europe under your designation of 'desert'. Equally parts of the
world I would describe as 'arid' do indeed have significantly more than
20" rainfall, particularly at low latitude with seasonal intense
rainfall.

In the UK, for example, were I blessed with 10" rainfall evenly spread
through the year to roughly match transpiration I would be growing
massive crops with nary a worry in the world.

Could be quite a tourist attraction too

Not much of a reply, can't you do better?

Equally someone with 30" of rain in low latitudes and high daytime
insolation and temperatures and with much of it coming erratically in a
few summer cloudbursts is going to be very arid indeed.

Equally someone with 90" of rain all of it coming in a single annual
cloudburst the rest of the year being dry and 40 centigrade. Remember
earth has certain design limits. Some conditions are rare if ever.

90" is not likely. Certainly 20" or more in a few rain sessions is not
so uncommon, particularly in continental areas at low latitudes. Runoff
is indeed typically severe but (being continental) they cover large
areas. Great tracts of asia (mongolia and around the himalaya) are
almost entirely pastoral.

The restriction of cropping isn't confined to low rainfall areas either.
Many areas that have shallow soils but high rainfall cannot be cropped.
Take a look at the west of england, particularly wales northward, and
you will find the vast majority of the farmed area cannot be cropped but
is good stock country. It's rather tricky cropping when you have a 90"
rainfall.

--
Oz
This post is worth absolutely nothing and is probably fallacious.
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