Introduction:
Rainfall is a natural phenomenon that occurs when water droplets fall from the Earth's atmosphere to the surface. It plays a crucial role in the water cycle and is essential for the survival of life on our planet. Rainfall is caused by a complex interaction of various factors, including atmospheric conditions and the movement of air masses.

1. Evaporation:
The first step in the formation of rainfall is evaporation. This process occurs when the sun's energy heats up the surface of water bodies such as oceans, lakes, and rivers. As a result, water molecules gain enough energy to break free from the liquid state and transform into water vapor, which rises into the atmosphere.

2. Condensation:
As the warm, moist air containing water vapor rises, it encounters cooler temperatures at higher altitudes. This causes the water vapor to lose heat energy and transform back into liquid droplets. The process of water vapor changing into liquid is known as condensation. These tiny water droplets form clouds in the atmosphere.

3. Cloud Formation:
Clouds are formed when millions of these condensed water droplets gather together in the atmosphere. They are visible because they reflect and scatter sunlight. Clouds can vary in shape, size, and altitude, depending on the atmospheric conditions.

4. Precipitation:
When the concentration of water droplets in a cloud becomes too high, the droplets start to collide and merge, forming larger drops. Eventually, these drops become heavy enough to fall through the air due to gravity. This process is known as precipitation.

5. Types of Precipitation:
Precipitation can take various forms depending on the temperature and atmospheric conditions. The most common types of precipitation include rain, snow, sleet, and hail. Rain occurs when the temperature is above freezing, while snow forms when the temperature is below freezing. Sleet is a mixture of rain and snow, and hail is formed when supercooled water droplets freeze and accumulate layers of ice.

Conclusion:
In conclusion, rainfall is caused by the continuous cycle of evaporation, condensation, cloud formation, and precipitation. It is a vital component of the Earth's water cycle and sustains ecosystems, agriculture, and human activities. Understanding the processes involved in rainfall helps us predict and manage water resources effectively.