he weather expert said, "is another true proverb, because
the description applies to thunderstorm clouds, when the rain is likely
to fall in frequent showers."

"It doesn't look like a regular rainy sky, though, Mr. Levin," said
Anton. "I thought rainy skies were usually heavy and gray."

"They are," the Forecaster answered, "and the Weather Bureau gives all
the rain clouds the general name of Nimbus, which simply means a thick
layer of dark clouds, without shape and with ragged edges, through which
rain or snow falls steadily. Sometimes, when there is a powerful wind in
the cloud layer, the lower edges of the clouds are broken apart, or
loose clouds are seen traveling fast under the overlying gray. Sailors
call this scud."

"Mr. Levin, suh," broke in Dan'l, "Ah knows a rhyme for scud, too," and
he quoted:

"Scud above and scud below
Shows there's goin' to be a blow."

"Well," said the Forecaster, hesitating, "that's not quite as good as
some of the others, because you don't see scud until the wind has
already come. As a whole, though, it's right, because it implies that
the atmospheric currents are powerful, and if the rain disappears, a
wind is likely to follow. I noticed you missed the rhyme about the rain
before the wind, in your article, Dan'l," he continued.

"Yas, suh!" the darky answered, "Ah don't know that one."

"It runs like this," the Forecaster answered:

"When the rain comes before the wind,
Be sure to take your topsails in,
When the wind comes before the rain,
You can put them on again."

"That's a good one, too, because high winds and steady rain seldom go
together.

"The last type of clouds, which is Number Ten in the Weather Bureau
Classification, is called Stratus. It really looks like a lifted fog,
which sometimes it is. Indeed, there is no essential difference between
clouds and fogs, anyway, except that fogs are formed at the surface and
clouds above it."

"All clouds are fogs, sir?" said Anton, in a surprised voice.

"Yes, my boy. Clouds are visible water vapor. Their visibility depends
largely on condensation, just as rain depends largely on the
dew-point."

"What's the dew-point, sir?"

"The dew-point," the Forecaster explained, "is the temperature at which
the air becomes so full of vapor that it can't hold any more without
letting it down as rain or snow. It's never the same any two days in
succession, because the air can hold more water vapor when