Lawson 1978
Lawson’s original criteria (published 1978) define five comfort categories from A (most comfortable) to E (least comfortable) using a uniform exceedance probability of 2% for the threshold wind speed.
In practical terms, each category sets a wind speed that should not be exceeded more than 2% of the time to be deemed acceptable for the corresponding activity. Any location where winds exceed that threshold more frequently is assigned to a poorer category (or marked as uncomfortable).
Lawson 1978 Comfort Categories
| Category | Wind Speed Threshold | Exceedance Probability | Typical Activity | Color |
|---|---|---|---|---|
| A | ≤ 1.8 m/s | ≤ 2% | Long-term Sitting (cafés, benches) | |
| B | ≤ 3.6 m/s | ≤ 2% | Short-term Sitting (standing implied) | |
| C | ≤ 5.3 m/s | ≤ 2% | Strolling | |
| D | ≤ 7.6 m/s | ≤ 2% | Business Walking | |
| E | > 7.6 m/s | > 2% | Uncomfortable |