Saharan Dust to the Amazon

 

 Concept:

At first, I planned to simulate a palm tree frond moving in the wind, but it started to feel like the project was only about appearance. While researching movement in nature, I found something more surprising: dust from the Sahara can travel across the Atlantic and help fertilize the Amazon rainforest. I chose this idea because it shows how tiny particles can move huge distances and create real environmental change. My sketch simulates dust being lifted, carried by wind, and settling in the Amazon, using simple physics rules (acceleration, velocity, and Perlin noise wind).

Reference video showing Saharan dust traveling from Africa to the Amazon rainforest (NASA).

Rules / How the Simulation Works:

1. Dust particles are released in short bursts, representing real dust storms.
2. Wind pushes the particles using smooth Perlin noise, so the motion feels natural.
3. All motion is controlled by acceleration, not by directly changing position.
4. When particles reach the Amazon side, a downward settling force pulls them down.
5. As dust settles, the Amazon area slowly becomes greener.
6. After one dust event (a “season”), the system fades out and restarts.

Code Highlight:

function drawBackground(season) {
  let desertCol = color(220, 200, 150);

  // Amazon color changes depending on fertility
  let amazonStart = color(55, 75, 55);   // dull green
  let amazonEnd   = color(35, 165, 80);  // vivid green
  let amazonCol   = lerpColor(amazonStart, amazonEnd, fertility);

  // 0) Fill whole canvas first (prevents any 1px gaps)
  noStroke();
  fill(desertCol);
  rect(0, 0, width, height);

  // 1) Draw smooth left→right gradient
  // Using 1px rectangles helps avoid “brown seam” line
  for (let x = 0; x < width; x++) {
    let t = x / (width - 1);
    let col = lerpColor(desertCol, amazonCol, t);
    fill(col);
    rect(x, 0, 1, height);
  }

  // 2) Fertility overlay on the Amazon side (soft edge)
  let startX = width * 0.6;
  for (let x = startX; x < width; x++) {
    let tt = map(x, startX, width, 0, 1);
    let a = tt * lerp(0, 200, fertility);
    stroke(20, lerp(70, 210, fertility), 60, a);
    line(x, 0, x, height);
  }

  // 3) Small warm tint that increases when season is “strong”
  noStroke();
  fill(255, 220, 180, 12 * season);
  rect(0, 0, width, height);
}

I chose this part of the code because it represents a decision I struggled with the most. I initially tried to use maps and detailed visuals to show Africa and South America, but they distracted from the movement of the dust. This background uses simple color transitions instead, allowing the particles’ behavior to tell the story. The Amazon only becomes greener when dust settles and increases the fertility value, which connects the visual change directly to the simulation rules.

Embedded Sketch: