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It's Raining! (Smart Water Cycle Condensation Terrarium)

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Build a sealed water cycle terrarium with a heated water reservoir (Sun) and ice lid (Cloud). A humidity sensor and temperature probe track condensation; when humidity hits 90%, mini LED rain drops flash and water droplets precipitate!

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Props & Materials Required

  • •Sealed clear acrylic terrarium container
  • •DHT22 temperature & humidity sensor
  • •Safe PTC heating pad (simulated solar heat, max 40°C)
  • •Top ice tray lid (cold atmosphere)
  • •ESP32 controller board with OLED display
  • •DFPlayer Mini MP3 module + 3W speaker

Step-by-Step Instructions

1

Set Up Water Cycle Terrarium

Add water and small plants inside the terrarium. Place ice on the top lid.

2

Turn ON Solar Heater Pad

Switch ON the bottom heater. Water warms up and begins EVAPORATING into invisible water vapor.

3

Watch Condensation Clouds Form

As vapor hits the cold ice lid, it CONDENSES into visible cloud droplets! DHT22 sensor reads humidity rising: '70%... 85%... 95%!'

4

Precipitation & Rain Audio

Water droplets become heavy and drip down as RAIN! Blue LEDs flash downward and speaker plays rain falling sounds: 'PRECIPITATION! The water cycle completed!'

Why It Works & Notes

The water cycle (evaporation → condensation → rain) is abstract when drawn on paper. Heating water at the bottom while cooling the top lid creates real visible water vapor clouds and condensation droplets inside the container.