Realistic Meteor Streak Visualization (2D): Drag, Ablation and Light Curve

Presets

Live readouts

Graphs

Radiated power against height (log scale)

Speed against height

Remaining mass fraction against height (log scale)

Numerical checks

running...

How to use

Choose a preset and press Restart. The white head travels down the path while the trail glows in proportion to the radiated power; the dashed marker shows where it is brightest. Try: (1) compare Perseid and Geminid: same size, but the fast, fragile Perseid peaks about 25 km higher; (2) use Dust grain and see a tiny, high, faint streak that burns out above 100 km; (3) raise the diameter and watch the peak sink and the body survive as a meteorite (the readout shows the remaining mass); (4) increase the zenith angle for a long, shallow streak; (5) change the observer distance and see the apparent magnitude change; (6) lower the heat-transfer coefficient to see how the burn-up height depends on how efficiently the body evaporates. Space pauses, R restarts.

The science

What happens to a meteor. A grain of rock hits the top of the atmosphere at 11 to 72 km/s. The air in front of it has no time to flow around, so the air molecules hit the surface directly: they slow the body (drag) and heat the surface until atoms boil off (ablation). The hot atoms collide with air, excite and glow: that glow, mostly from the evaporated metals, is the streak. A simple "single-body" model captures the whole picture with three equations.

1. Atmosphere. Density falls roughly exponentially with height: ρ_a(h) = ρ₀ exp(-h/H), with ρ₀ = 1.225 kg/m³ and an effective scale height H = 7.16 km (a good fit between 60 and 130 km; below that the temperature structure matters).

2. Drag. With cross-section A = 1.21 (m/ρ_m)^2/3 (a sphere) and drag coefficient Γ:

dv/dt = - Γ ρ_a v² A / m

The path is a straight line at zenith angle z, so dh/dt = -v cos z. If the mass were constant the equation can be solved exactly: ln(v/v₀) = - K H ρ_a(h) / cos z with K = Γ 1.21 / (m^1/3 ρ_m^2/3). The meteor keeps nearly its entry speed until the air in front of it weighs about as much as the body, then it brakes sharply. The body loses its speed over a short height range, the "deceleration height".

3. Ablation. The kinetic energy flux hitting the surface is (1/2) ρ_a v³ A. A fraction Λ of it vaporises mass at a cost ζ (heat of ablation, about 6 MJ/kg for stony, 8 for iron, 2.5 for comet dust):

dm/dt = - Λ A ρ_a v³ / (2 ζ)

Without deceleration this also has a closed form: m^1/3(h) = m₀^1/3 - B ρ_a(h) H / (3 v cos z), B = Λ 1.21 v³ / (2 ζ ρ_m^2/3).

Ablation only starts once the surface is hot enough to evaporate: when the absorbed flux (1/2) Λ ρ_a v³ exceeds the thermal emission at about 2200 K (about 1.2 MW/m²); that sets the height where a meteor first lights up.

4. Light. The radiated power is a small fraction τ (luminous efficiency, about 0.1 to 5 %, rising with speed) of the kinetic energy carried away by the ablated atoms: I = -τ (dm/dt) v²/2. In astronomical units, magnitude M = -2.5 log₁₀(I / 1500 W) at a range of 100 km (a 0-magnitude meteor radiates roughly 1500 W), and the apparent magnitude changes by 5 log₁₀(range / 100 km). The streak is brightest where the product of air density and remaining mass is optimal: higher for small, fast, fragile grains, lower for big, dense, slow bodies (compare the Perseid and Geminid presets).

Checks (run in the page). (1) with ablation off, the numerical integrator reproduces the closed-form v(h) to better than 0.4 % between 30 and 110 km; (2) with drag off, it reproduces the closed form m^1/3(h) to better than 0.4 % of the initial value; (3) halving and quartering the time step changes the peak luminosity by under 1 %.

Simplifications. A single non-rotating sphere with no fragmentation (real meteors often break up, especially cometary ones and large bolides such as Chelyabinsk), constant coefficients Γ, Λ, τ (real τ depends on speed and mass), a flat Earth with an exponential atmosphere, no wind, no deceleration due to the heated shock layer, and no dark-flight phase. Values are order-of-magnitude teaching numbers, not a reconstruction of a real event.