The phrase "when did the raindrops begin to fall?" is subjective and depends on the context. If you are asking about the general phenomenon of rain, it's believed to have started billions of years ago when the Earth's atmosphere cooled enough to allow condensation.

However, if you're referring to a specific event, like a rainstorm, you would need to provide more details to get a specific answer.

Here's a breakdown of how rain forms in general:

• Evaporation: Water evaporates from bodies of water (oceans, lakes, rivers) and the land, turning into water vapor.
• Condensation: As the water vapor rises and cools, it condenses into tiny water droplets or ice crystals, forming clouds.
• Precipitation: When these droplets or ice crystals become heavy enough, they fall back to Earth as rain, snow, sleet, or hail.

For a more detailed explanation of the water cycle, you can refer to resources like:

• The Water Cycle | U.S. Geological Survey