Skip to content

Rain Shadow Effect Visualizer

Run the Rain Shadow Effect Visualizer MicroSim Fullscreen
Edit in the p5.js Editor

About This MicroSim

This MicroSim visualizes the rain shadow effect -- one of the most important processes shaping terrestrial biome distribution. Students observe animated air parcels flowing from an ocean across a mountain range, watching as the air rises on the windward side, cools adiabatically, forms clouds, and releases precipitation. On the leeward side, the descending air warms and dries, creating arid conditions.

The mountain height slider (500m to 5000m) lets students discover that taller mountains produce more extreme rain shadows. Vegetation changes dynamically with moisture levels: lush green forests on the windward slope give way to sparse brown scrubland on the leeward side. Temperature and humidity labels update at each stage of the process.

A "Real Examples" dropdown overlays data from actual mountain ranges including the Cascades, Sierra Nevada, Himalayas, and Andes, connecting the model to real geography that students can find on a map. This simulation makes the invisible processes of atmospheric moisture transport visible and intuitive.

How to Use

  1. Observe the animated cross-section showing ocean, mountain, and lowlands.
  2. Watch the blue air parcels flow from left to right, forming clouds and rain on the windward side.
  3. Adjust the Mountain Height slider (500m-5000m) and observe how taller mountains create stronger rain shadows.
  4. Note the temperature and humidity readings at different stages of air flow.
  5. Use the Real Examples dropdown to see how actual mountain ranges compare (Cascades, Sierra Nevada, Himalayas, Andes).
  6. Observe how vegetation changes between the wet windward side and the dry leeward side.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

1
2
3
4
<iframe src="https://dmccreary.github.io/ecology/sims/rain-shadow/main.html"
        height="477px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

9-12 (High School Biology / AP Environmental Science)

Duration

45 minutes

Learning Objectives

  • Explain how mountain ranges create wet and dry climate zones through the rain shadow effect.
  • Describe the process of adiabatic cooling and warming as air moves over terrain.
  • Predict how mountain height affects precipitation patterns and biome distribution.
  • Connect rain shadow effects to real-world geography and ecosystem distribution.

Prerequisites

  • Basic understanding of the water cycle (evaporation, condensation, precipitation)
  • Familiarity with biomes and climate zones
  • Understanding of how temperature affects air moisture capacity

Standards Alignment

  • NGSS ESS2.D: Weather and Climate
  • AP Environmental Science: Topic 1.1 - Introduction to Ecosystems; Topic 4.3 - Weather and Climate

Activities

  1. Engage (5 min): Show satellite images of the Cascade Range in Washington state. Ask students why the western side is lush rainforest while the eastern side is dry grassland, even though they are only miles apart. Introduce the rain shadow concept.

  2. Explore (15 min): Students run the simulation at different mountain heights and record the temperature and humidity values on both sides. They compare results for the Cascades vs. the Himalayas using the Real Examples dropdown. Students sketch the process and label key stages.

  3. Explain (15 min): Discuss adiabatic lapse rates: air cools approximately 6.5C per 1000m as it rises, clouds form when temperature reaches the dew point, and descending air warms and dries. Connect to global precipitation patterns and explain why many of the world's deserts are located in the rain shadow of major mountain ranges (Gobi Desert, Patagonian Desert, Great Basin).

  4. Extend (10 min): Students predict what would happen to the Willamette Valley ecosystem if the Cascade Range were suddenly twice as tall. They write a paragraph explaining how the rain shadow effect influences where different biomes are found and why biodiversity patterns differ on opposite sides of mountain ranges.

Assessment Questions

  1. Explain step by step what happens to an air parcel as it moves from the ocean, over a mountain, and down the other side.
  2. Why is the leeward side of a mountain range typically drier than the windward side?
  3. If climate change were to significantly reduce the height of a mountain range through glacial erosion, how would the rain shadow effect change? What would happen to ecosystems on both sides?
  4. Name a real-world rain shadow and describe the ecosystems found on each side of the mountain range.

References

  1. Ahrens, C.D. (2018). Meteorology Today, 12th ed. Cengage Learning.
  2. Roe, G.H. (2005). Orographic precipitation. Annual Review of Earth and Planetary Sciences, 33, 645-671.
  3. NOAA: Rain Shadow Effect. https://www.noaa.gov/