Fly into the Eye · TyphoonLab

Grow a typhoon yourself: tune sea temperature, wind shear and latitude and watch the disturbance grow or die out; release tracer particles to see how the Coriolis force sets it spinning; ride a reconnaissance aircraft through the eyewall into the calm eye, then climb all the way to space to see the white spiral; finally use real tracks such as Lekima and Mangkhut to judge when a city's wind peaks, how its direction turns, and why the rain can stay heavy after landfall even as the wind weakens.

Subject: Geography · Level: High school · Topics: How typhoons form, Coriolis force and spin direction, Eye, eyewall and spiral rainbands, Tracks and decay after landfall

Chapters

Grow a typhoon

A typhoon is a strong tropical cyclone that develops over tropical oceans. To grow, it needs three things: warm sea water for energy, little difference between the winds aloft and below (weak vertical wind shear), and enough Coriolis force to make the air spin.

First judge how three sets of conditions will end, then run a 72-hour time-lapse for each and watch the intensity curve. Finally, tune your own typhoon.

Why it spins

Air flows from all around towards the low pressure at the centre. In the Northern Hemisphere, moving air is deflected to the right by the Coriolis force.

First predict which way the typhoon turns as seen from space, then release tracer particles and switch on the force arrows. Next, drag the typhoon into the Southern Hemisphere, and then close to the equator.

Fly into the Eye

You will ride a weather reconnaissance aircraft at 3 km altitude from the edge of the typhoon all the way to its centre.

Before take-off, sketch how you think wind speed and pressure will change. In flight, press Space to drop a dropsonde: one in a rainband, one in the eyewall and one in the eye. After landing, mark where the wind is strongest on the curve.

Climb to space

Climb from the eye all the way to 5000 km to see the whole typhoon.

Once in space, click the parts of the typhoon: the eye, the eyewall, the spiral rainbands and the upper-level outflow cloud. Then open the cross-section to see how air rises, sinks and flows out.

Follow the track

Choose a real typhoon and a city, then drag the timeline to see how the city's wind speed and direction change.

Predict first: when is the wind strongest, and how does its direction turn? Then play it back to check. Try cities right of, left of and on the track.

After landfall

After landfall the typhoon loses the moisture and heat of the warm sea, and friction over land is high, so the wind weakens quickly. But weaker wind does not always mean less rain.

Predict first, then compare the "stays at sea" and "makes landfall" curves, and finally check real cases.

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