Windward vs Leeward Side Calculator
Estimate how air cools as it rises up the windward side of a mountain and warms as it descends the leeward side, including cloud base height and the rain shadow effect.
Why The Leeward Side Is Warmer and Drier
Enter the starting air temperature, dew point and mountain height. The calculator uses dry and moist adiabatic lapse rates to estimate conditions on both sides of the mountain.
Orographic Lift & Rain Shadow Estimator
Apply adiabatic cooling and warming to see the temperature gap between each side.
Understanding Windward and Leeward
Key concepts for orographic weather
Windward Side
The side facing the wind. Air is forced upward, cools and condenses into clouds and rain or snow, so this side is typically wet and cloudy.
Leeward Side
The sheltered side. Descending air warms and dries, creating a rain shadow, with warm, dry foehn or chinook winds.
Adiabatic Lapse Rates
Unsaturated air cools about 9.8 °C per km as it rises. Once saturated, it cools more slowly at roughly 4 to 7 °C per km because condensation releases heat.
Why It Matters
Rain shadows create deserts and dry valleys such as the Atacama, Patagonia and the Great Basin, while windward slopes support rainforests and heavy snowfall.
Windward vs Leeward Quick Comparison
A summary of the typical differences between the two sides of a mountain range.
| Feature | Windward Side | Leeward Side | Example |
|---|---|---|---|
| Rainfall | High | Low (rain shadow) | Snowdonia vs Cheshire plain |
| Temperature | Cooler | Warmer (foehn) | Alps vs Swiss valleys |
| Cloud Cover | Frequent | Often clear | Cascades, USA |
| Vegetation | Lush forest | Dry grassland or desert | Sierra Nevada, USA |
| Winds | Rising, moist | Descending, dry | Chinook, Canada |
| Net Effect | Wet, cool, green | Dry, warm, sparse | Rain shadow |
Windward vs Leeward FAQ
Answers to common questions about windward and leeward weather.
The windward side faces the oncoming wind and is usually wet, while the leeward side is sheltered from it, typically drier and warmer.
A rain shadow is a dry region on the leeward side of a mountain range, created because air loses most of its moisture as precipitation on the windward side.
Air that has dropped its moisture on the windward slope warms at the faster dry rate (9.8 °C per km) while descending, so it ends up warmer than it started. This is called the foehn effect.
A simple rule is cloud base in metres ≈ 125 × (air temperature − dew point in °C). This calculator uses that rule to estimate where condensation begins.