Model plume spread, stack effects, and receptor exposure. Review assumptions, stability choices, and outputs clearly. Download clean reports with tables for reviews and records.
| Scenario | Class | x (m) | y (m) | Effective height (m) | Sigma y (m) | Sigma z (m) | Receptor concentration (ug/m3) |
|---|---|---|---|---|---|---|---|
| Lab vent screening | C | 500.00 | 0 | 22.0000 | 53.6745 | 38.1385 | 187.99249662 |
| Process stack review | D | 1,000.00 | 100.00 | 43.0000 | 76.2770 | 37.9473 | 65.35747755 |
| Stable night check | F | 1,500.00 | 50.00 | 34.0000 | 55.9503 | 16.5517 | 81.75574041 |
The calculator uses the steady state Gaussian plume equation for a continuous point source.
C(x,y,z) = Q / (2πuσyσz) × exp[-y² / (2σy²)] × {exp[-(z - H)² / (2σz²)] + exp[-(z + H)² / (2σz²)]}
H = hs + dh
Q is emission rate. u is wind speed. σy and σz are lateral and vertical dispersion coefficients. H is effective stack height. The reflection term accounts for plume behavior near the ground.
The page uses standard rural stability relationships for classes A through F to estimate sigma y and sigma z as downwind distance changes.
A Gaussian dispersion model calculator estimates pollutant concentration downwind from a stack or vent. It is useful for chemistry studies, emission screening, and process safety checks. This page helps you model plume behavior with receptor coordinates, stability class, wind speed, and effective stack height. It gives fast output for concentration, travel time, and dispersion widths.
Chemical releases do not stay at the source. Wind transports them. Atmospheric turbulence spreads them. Stack height and plume rise also change exposure at ground level. A good screening model helps teams compare scenarios before detailed field work. It supports air quality reviews, laboratory planning, and environmental compliance preparation.
This calculator uses emission rate, wind speed, downwind distance, crosswind distance, receptor height, physical stack height, plume rise, and stability class. These values define where the receptor sits and how the atmosphere mixes the plume. The model then calculates sigma y and sigma z with standard rural stability relationships.
The main result is receptor concentration. It is reported in grams, milligrams, and micrograms per cubic meter. The page also returns effective stack height, lateral spread, vertical spread, and ground centerline concentration. These extra outputs make sensitivity checks easier when you test several release cases.
Use this tool for preliminary assessments, training, design comparisons, and educational chemistry work. It is especially helpful when you need a transparent calculation path. The included formula section explains each term clearly. The example data table also shows how a realistic scenario can be entered and reviewed.
Stability class strongly affects plume spread. Unstable air usually mixes faster and lowers centerline concentration at many distances. Stable air mixes less and can increase narrow plume impacts. Test multiple classes when meteorological conditions are uncertain and compare the concentration range.
This calculator is a screening aid, not a substitute for a full regulatory study. Real sites may need terrain effects, building downwash, deposition, chemical reaction, and time varying meteorology. Even so, a Gaussian plume estimate remains valuable for fast decision support and technical communication.
Q depends on your source. Many screening examples use grams per second. Keep wind speed in meters per second and all distances in meters so the concentration output stays consistent.
A changes fastest. F changes slowest. Unstable air spreads the plume more. Stable air keeps it narrower. Choose the class that best matches your meteorological assumptions.
Plume rise increases effective stack height. A higher effective release point usually lowers ground level concentration near the source and can shift the maximum impact farther downwind.
Yes. Set crosswind distance to zero and receptor height to zero. The calculator also reports a separate ground centerline value for quick comparison.
Sigma y describes lateral spread. Sigma z describes vertical spread. Both grow with distance, but the rate depends on atmospheric stability.
No. It is a screening tool. Regulatory modeling may require site specific meteorology, terrain treatment, downwash, chemistry, and approved software workflows.
A negative crosswind value gives the same concentration magnitude as a positive value of equal distance because the equation uses the squared crosswind term.
The page opens the browser print dialog. From there, save the report as a PDF. This keeps the output simple and easy to review.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.