How a Tropical Cyclone Forms, Strengthens and Weakens: Orbit-to-Eyewall Lab with SST, Shear and Coriolis

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terrain, textures, coastal town

Scenario

Environment (applied at restart; most also live)

Sea-surface temperature (basin warm pool)Genesis threshold ~26.5 C. Poleward the water cools about 0.3 C per degree of latitude.

Vertical wind shear (850-200 hPa)Tilts and ventilates the storm; above ~12 m/s it usually tears it apart.

Genesis latitudeCoriolis f = 2 Omega sin(lat). Below about 5 degrees there is almost no spin to grow.

Mid-level moisture (relative humidity)Dry air entrained into the core weakens rainbands and the eyewall.

Allow eyewall replacement cycles

Show storm track

Show latitude lines

Map layer

Map legend

Saffir-Simpson category (1-min sustained wind)

Camera: drag = orbit, wheel / pinch = zoom (orbit to eyewall to a coastal street), shift-drag or two fingers = pan. The view buttons fly to preset zoom levels.

Live readouts

Wind and pressure profile (Holland 1980)

Storm surge at the harbour town (inanimate coast)

Intensity vs time

Bars show the Saffir-Simpson bands. Solid = current sustained wind (left axis), thin line = central pressure (right axis), dashed = the intensity the environment would support right now (sea temperature, shear, moisture, latitude). Markers: eyewall replacement (E), landfall (L).