This is the 2D map-view companion to the 3D "Cyclone & Coriolis Effect" laboratory. Instead of an arbitrary hemisphere sign, every parcel here is pushed by a Coriolis acceleration computed from the real latitude-dependent Coriolis parameter, integrated frame by frame — nothing about the spiral is drawn or scripted.
Coriolis parameter: f = 2*Omega*sin(latitude)
Coriolis accel: a_cor = -f * (-v_y, v_x) (deflects right in N, left in S)
Pressure gradient: a_pg = K_inflow / r^2 (toward low, away from high)
v(t+dt) = v(t) + (a_pg + a_cor)*dt
x(t+dt) = x(t) + v(t+dt)*dt
Omega (Earth) = 7.2921e-5 rad/s
- Latitude genuinely sets the strength of the Coriolis term through sin(latitude): drag it to 0° and f drops to exactly zero — parcels then flow straight into the low with no rotation at all, exactly as at the real equator.
- Hemisphere flips the sign of f, reversing the deflection: right-of-motion (Northern, counter-clockwise cyclones) vs. left-of-motion (Southern, clockwise cyclones).
- Low vs. high flips the pressure-gradient term from inward to outward, so the same Coriolis deflection produces the opposite sense of spiral for a cyclone vs. an anticyclone in the same hemisphere.
- The Rossby number Ro = U/(f*L) reported live compares inertial to Coriolis forces for the current parcel speed and radius — this is the same dimensionless number that explains why a cyclone's rotation is real physics but a draining bathtub's is not.
Mechanically this differs from the 3D lab: there, Coriolis strength is an arbitrary 0–3× multiplier and hemisphere is a flat sign; here it is derived from an actual latitude via f = 2*Omega*sin(latitude), so the equatorial vanishing point is a real, adjustable feature of the model rather than a fixed toggle.