What do pilots do when a storm is coming?

The short version

A thunderstorm is a cloud that has grown enormous. It starts as a puffy heap on a warm day and keeps building as warm, damp air rushes up inside it, until it is often taller than the highest mountains, with a flat top spread out like a blacksmith’s anvil. Inside, air races up and pours down at the same time, rain and hail form, lightning flashes, and thunder is the sound the lightning makes.

How can you tell a storm is coming?

• The clouds pile up high and turn dark underneath.
• The light changes: the sky goes dim, sometimes with a strange tint to it.
• The air suddenly turns cooler and a gust of wind arrives, often just before the rain. That cold gust is air rushing out from underneath the storm.
• You hear thunder. If you can hear it, the storm is close.

What makes thunder and lightning?

Inside a storm cloud, tiny crystals of ice and little pellets of soft hail are flung up and down past one another, and as they bump they build up electricity, the same kind that crackles when you pull a woolly jumper off over your head. When enough has built up, it jumps, inside the cloud or down to the ground, as one giant spark. That spark is lightning.

It heats the air it passes through in a flash, to several times hotter than the surface of the sun, and the hot air bursts outwards with a bang. That bang is thunder: a sharp crack close by, and a long, low rumble far away.

How far away is the storm?

First things first: if you can hear thunder at all, you are close enough for lightning to reach you, so it is time to go inside. A proper building is best, or a car with a metal roof and the windows shut. Stay there until half an hour after the last thunder.

Then, from indoors, you can work out how far away it is. Light reaches you almost at once, but sound is slower: it takes about three seconds to travel a kilometre, and about five to travel a mile. So when you see a flash through the window, count the seconds until the thunder and divide by three. That is roughly how many kilometres away the lightning was. If the count gets shorter each time, the storm is coming closer.

Do aeroplanes fly through thunderstorms?

Pilots take thunderstorms more seriously than almost anything else in the sky, because the air in and around them is violently bumpy, and there can be hail and lightning. So they do not fly into them. Before a flight they read the forecast and look at the weather radar. In the air they give a storm a very wide berth, many kilometres, and fly around it, or turn back, or land somewhere and wait. Even the biggest airliners go around thunderstorms.

Turning back is not giving up. Pilots plan for it before they take off, deciding where they will turn round if the weather is wrong, and a pilot who turns back from a storm has made a good decision that every other pilot respects.

How long does a thunderstorm last?

A storm cannot keep going for ever. It is fed by warm air rising into it, and once the rain, and the cold air falling with it, pour down harder than the warm air can rise, the storm is cutting off its own supply. It rains itself out. Most single thunderstorms are over in less than an hour: the cloud thins, the rain eases, and the sun comes back through. Often the wisest thing to do about a storm is to wait for it.

In the story

Everything above is what real pilots do. This part is Little Blue’s world: in the book’s own words, “A story about a small dream meeting fear, storms, and learning to read the weather.”

Chapter seven has every sign above, in the order a pilot would notice them: the cold air, the changing light, the wall of cloud ahead. Little Blue’s heart beats fast, and two voices argue inside him. One says “Turn back.” The other, braver, says “Keep looking ahead.”

In a real aeroplane there is no argument. Keeping your eyes on what is ahead is how a pilot reads the weather, and when what is ahead is a thunderstorm, a real pilot turns back or goes around it, every time. Little Blue flies on because this is a story: his storm is the book’s way of showing a very small pilot finding his courage, not a lesson in how to fly. In Read the Storm the little pilot wonders it out loud, I think I’ll just… turn back?, and the song never calls that cowardly.

In chapter eleven the storm ends the way storms do. The clouds open “like a curtain pulling back,” the sun comes through, and the chorus of Read the Storm turns out to have been telling the truth all along: the storm will tire out first, little bird… not you.

Three words to keep

• Thunderstorm: a towering cloud with lightning, thunder, heavy rain and very rough air inside.
• Anvil: the flat, spread-out top of a thunderstorm cloud.
• Divert: to fly somewhere other than planned, because of the weather or anything else. A good decision, not a failure.

Why storms shake an aeroplane so much: what is turbulence?