MARITIME – AFETY, URVIVAL & RECUE CALCULATOR
Flare Visibility Range
A precise tool.
What is the Flare Visibility Range & How does it work?
Parachute flares emit a high‑intensity light source that can be seen over long distances. The intrinsic intensity (I) of the flare, measured in candela, determines the amount of luminous energy released and is the primary driver of visibility. Atmospheric transmissivity (T) describes how much of that light reaches an observer after scattering and absorption by air molecules, aerosols, and humidity. Clear, dry conditions give T values close to 1, while fog or haze can reduce T dramatically. The human eye’s ability to detect the flare depends on the background luminance (B). During daylight the sky and sea provide a bright background, lowering contrast, whereas at night the background is much darker, allowing the flare to be seen from farther away. Combining these factors yields the visibility range formula shown below.
R = sqrt{frac{I cdot T}{B}}
R = visibility range (km)
I = flare intensity (candela)
T = atmospheric transmissivity (0–1)
B = background luminance (candela/m²)
I = flare intensity (candela)
T = atmospheric transmissivity (0–1)
B = background luminance (candela/m²)
Parameters
Result
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Frequently Asked Questions
What is intrinsic intensity in a flare?
Intrinsic intensity (I) is the light output of a flare measured in candela, indicating how much luminous energy it releases.
How does atmospheric transmissivity affect visibility?
Atmospheric transmissivity (T) describes how much of the flare's light reaches an observer after being scattered or absorbed by air molecules and other particles. Clear conditions have high T values, while fog or haze reduce it significantly.
Can you explain the formula used to calculate visibility range?
The visibility range is calculated using the intrinsic intensity of the flare and atmospheric transmissivity, taking into account how light travels through the atmosphere.
What factors can reduce the visibility range of a flare?
Factors such as fog, haze, humidity, and air pollution can reduce the visibility range by decreasing atmospheric transmissivity.
How important is intrinsic intensity in determining visibility?
Intrinsic intensity is crucial as it directly affects how much luminous energy a flare emits, which in turn determines its visibility over distance.
Results are for informational purposes only and do not constitute professional advice.