Soil erosion by action of rain can be caused by all of the following except

Soil erosion by rain can occur when the force of raindrops and the resulting surface runoff remove the top layer of soil. This process can be harmful and lead to the loss of fertile soil needed for growing crops and plant growth. There are several factors that can contribute to soil erosion by rain, but one of the options mentioned does not cause it. Let's analyze each option:

Tropical rainstorms: Tropical rainstorms are often associated with heavy rainfall and intense precipitation. The large amount of rainwater can create powerful runoff that can wash away soil particles and contribute to erosion. Therefore, tropical rainstorms can indeed cause soil erosion by rain.

Scanty vegetation: Vegetation, such as plants and trees, plays a crucial role in preventing soil erosion. The roots of plants help hold the soil together, reducing the impact of raindrops and preventing excessive runoff. When vegetation is sparse or absent, there are no roots to anchor the soil, making it more vulnerable to erosion. So, scanty vegetation can contribute to soil erosion by rain.

Steep slopes: Steep slopes can accelerate the process of soil erosion by rain. When rainwater flows down a steep slope, it gains momentum and power, increasing the force with which it hits the soil. This force can dislodge soil particles and carry them away, leading to erosion. Therefore, steep slopes can cause soil erosion by rain.

Aridity: Aridity refers to dryness or a lack of moisture. In arid regions, rainfall is limited, and the soil may be dry and less prone to erosion caused by rain. The lack of significant rainfall reduces the chances of soil particles being dislodged by raindrops or carried away by runoff, making aridity a factor that does not cause soil erosion by rain.

In conclusion, all the options except aridity can contribute to soil erosion by rain. Tropical rainstorms, scanty vegetation, and steep slopes can all increase the likelihood of soil erosion. However, in arid regions where there is a lack of moisture, the risk of soil erosion caused by rain is reduced.