"During thunder, we can hear a rolling sound." Why?

Answer

To understand why we hear a rolling sound during thunder, we can break down the explanation into several steps:

### Step 1: Lightning Occurs
When lightning strikes, it creates a sudden discharge of electricity in the atmosphere. This discharge generates an immense amount of heat.

### Step 2: Increase in Temperature
The heat from the lightning causes the air molecules around it to rapidly increase in temperature. This sudden rise in temperature leads to a significant increase in the pressure of the surrounding air.

### Step 3: Movement of Air
As the air heats up, it becomes less dense and rises. Meanwhile, the cooler, denser air moves down to take its place. This movement creates a convection current.

### Step 4: Creation of Pressure Waves
The rapid expansion of hot air creates pressure waves. These waves propagate through the atmosphere, resulting in the sound we hear as thunder.

### Step 5: Sound Reflection and Diffraction
As the sound waves travel, they encounter various obstacles such as buildings, trees, and the ground. These obstacles cause the sound waves to reflect and diffract, leading to multiple paths for the sound to reach our ears.

### Step 6: Prolonged Sound Effect
Due to the reflections and the different paths taken by the sound waves, we hear the thunder as a prolonged sound. This effect is what we refer to as a "rolling sound," as it seems to roll on for a longer duration rather than being a sharp, single clap.

### Conclusion
Thus, the rolling sound of thunder is a result of the initial pressure waves created by the lightning, combined with the reflections and diffractions of those sound waves as they travel through the atmosphere.

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