Collision Coalescence Warm Rain Growth
Integrate ideal spherical collector growth under constant relative fall speed, liquid content and efficiency, conserving gained liquid mass; no droplet spectrum, changing fall speed or rain onset prediction.
Description
Collision and coalescence can enlarge a spherical collecting drop as it sweeps cloud liquid.
Collision and coalescence can enlarge a spherical collecting drop as it sweeps cloud liquid. A constant-flux model assumes fixed relative speed, efficiency and liquid-water content.1
Integrate ideal spherical collector growth under constant relative fall speed, liquid content and efficiency, conserving gained liquid mass; no droplet spectrum, changing fall speed or rain onset prediction.
When to use Collision Coalescence Warm Rain Growth
Use this tool to integrate ideal spherical collector growth under constant relative fall speed, liquid content and efficiency, conserving gained liquid mass; no droplet spectrum, changing fall speed or rain onset prediction.
Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.
How to use Collision Coalescence Warm Rain Growth and understand its results
- Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.
- Enter initialCollectorRadiusM, cloudLiquidWaterKgPerM3, collectionEfficiencyFraction, relativeFallSpeedMPerSecond, collectionDurationSeconds, liquidDensityKgPerM3 using the field table and calculation rules, then run the tool.
- Read constantFluxRadiusGrowthMPerSecond, modelFinalCollectorRadiusM, modelCollectedLiquidMassKg. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| initialCollectorRadiusM | Initial collector radius m | number | Required |
| cloudLiquidWaterKgPerM3 | Cloud liquid water kg per m3 | number | Required |
| collectionEfficiencyFraction | Collection efficiency fraction | number | Required |
| relativeFallSpeedMPerSecond | Relative fall speed m per second | number | Required |
| collectionDurationSeconds | Collection duration seconds | number | Required |
| liquidDensityKgPerM3 | Liquid density kg per m3 | number | Required |
Use positive initial radius and liquid density, nonnegative content, speed and duration, and efficiency in [0,1]. Grow radius linearly; compute gained liquid mass from the difference in spherical volumes using an expanded expression that avoids cancellation.
radius growth rate = efficiency × liquid content × relative speed/(4 × liquid density) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| constantFluxRadiusGrowthMPerSecond | Constant flux radius growth m per second | number |
| modelFinalCollectorRadiusM | Model final collector radius m | number |
| modelCollectedLiquidMassKg | Model collected liquid mass kg | number |
{
"input": {
"initialCollectorRadiusM": 0.001,
"cloudLiquidWaterKgPerM3": 0.001,
"collectionEfficiencyFraction": 0.5,
"relativeFallSpeedMPerSecond": 2,
"collectionDurationSeconds": 100,
"liquidDensityKgPerM3": 1000
},
"output": {
"constantFluxRadiusGrowthMPerSecond": 2.5e-7,
"modelFinalCollectorRadiusM": 0.001025,
"modelCollectedLiquidMassKg": 3.2207869683990444e-7
}
}Limitations and assumptions
No evolving drop spectrum, changing fall speed or rain-onset prediction is modeled.
Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Hail Kinetic Energy Damage Proxy: Sum spherical caller hail inventory kinetic energy per represented impact area; impact speeds are supplied, not terminal-speed lookup, and energy alone is not a damage, injury or safe-shelter prediction. For a complementary task, use Precipitable Water Column: Integrate supplied specific humidity over increasing pressure in measured column with gravity/liquid density conversion; partial observed column remains partial and condensate or unsampled atmosphere is not inferred.
References
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Collision Coalescence Warm Rain Growth — tool.io
Similar or alternative tools
- Hail Kinetic Energy Damage Proxy
Sum spherical caller hail inventory kinetic energy per represented impact area; impact speeds are supplied, not terminal-speed lookup, and energy alone is not a damage, injury or safe-shelter prediction.
- Precipitable Water Column
Integrate supplied specific humidity over increasing pressure in measured column with gravity/liquid density conversion; partial observed column remains partial and condensate or unsampled atmosphere is not inferred.