Chapter 29. About Lightning

Lightning is born from the friction of clouds, as [sparks] are born from the collision of stones, and after them comes thunder, but the sound reaches the ears later, than the brilliance reaches the eyes. After all, the collision of any objects causes fire. However, some say that the lower layers of the air contain water due to evaporation, and the upper layers contain fire due to the heat, and whenever they collide with each other, there is a terrifying crash of thunder. And if the fire wins at the same time, then there will be no harvest, but if there is water, then there will be abundance. And the fire of lightning has greater power [in comparison with earthly fire] because it consists of finer elements than that which we use.

Chapter 30. When they don't happen and why

In winter and summer, lightning is rare, as the frosty air extinguishes all the fire that falls into it. In hot summers, vapors rarely condense into clouds, and even then into rarefied ones, and without dense clouds there is no lightning. It is this circumstance that protects Scythia [22] and Egypt from lightning, while Italy is subject to them in the highest degree, because, on account of the mild winters and rainy summers, spring and autumn seem to reign there all the time.

Chapter 31. About the rainbow

A four-coloured rainbow in the air is formed by the sun and the clouds opposite it: a ray of sunlight falling into a hollow cloud is reflected and refracted into the sun, just as the pattern of a ring is reproduced on wax; At the same time, he [the ray] borrows the fiery color from the sky, purple from the waters, hyacinth from the air, and grass from the earth. [A rainbow] is less frequent in summer than in winter, and rarely at night, except at a full moon, when it reflects the moonlight.

Chapter 32. About clouds

The clouds are gathered from the air that has condensed into droplets: for the air, by its natural lightness, lifts up the water vapours of the earth and the sea, consisting of the smallest droplets, and keeps them at a height, where, whether boiled by the fire of the sun, or changed by the air they have traveled, they all become fresh: thus we, wishing to change the taste of the water, usually pour sea-water into the earth. and unleavened into sea grasses.

Chapter 33. About rains

Rains grow from cloud droplets: they gradually gather into large droplets, and the air nature can no longer withstand them; Then, in large numbers, they immediately roll down to the ground, sometimes torn off by the wind, then melting under the rays of the sun. Actually, we call slow and prolonged rains, and sudden and rapid rains. [150]

Chapter 42. About the Red Sea

The Red Sea is so called because of its pink-red color, which, however, is not inherent in it by nature - its water is colored so because of the neighboring shores of a blood-red color. [And, however, it may be the other way around:] it was from the name of this [sea] that surik, and other [red] paints, and precious stones [rubies] began to be called "red". This sea is divided into two gulfs, of which the Persian Gulfs face Aquilon,23 and the Arabian Gulf, the latter being 115 miles from the Egyptian Sea.

Chapter 43. About the Nile

The Nile River, whose source is between sunrise and Austrom,24 serves the inhabitants of Egypt instead of rain, because there is scarcely any rain or cloud on account of the heat of the sun. In the month of May, when Zephyr blows,25 and the waves, throwing out sand, encumber the mouth through which it flows into the sea, the Nile gradually swells, and, forced to move back, irrigates the plains of Egypt; when the wind stops, it breaks through the piles of sand and returns to its bed.