Feathers on birds’ bodies can keep birds warm. Which of the following statements describes the main reason? *
Feathers are poor conductor of heat so that the rate of heat lost by conduction is reduced.
Feathers are always white in color so that the rate of heat lost by radiation is reduced.
Feathers trap air so that the rate of heat lost by convection is reduced.
The correct answer and explanation is :
The correct answer is:
Feathers trap air so that the rate of heat lost by convection is reduced.
Explanation:
Feathers play a vital role in regulating a bird’s body temperature, primarily by reducing heat loss. This is achieved through their ability to trap air close to the bird’s skin. The trapped air acts as an insulating layer, preventing the heat from escaping the bird’s body and thus conserving warmth. This process is especially crucial for birds living in colder environments.
To understand why this is the main reason, let’s first review the three modes of heat transfer:
- Conduction: The transfer of heat through direct contact between objects. Feathers are not the best conductors of heat, so they help minimize heat loss through conduction. However, this is not the primary reason feathers keep birds warm because the major mechanism of heat loss in birds is through convection.
- Radiation: Heat can also be lost through radiation, where heat is emitted in the form of infrared radiation. The color of the feathers can play a minor role in radiation (e.g., dark feathers absorbing more heat), but this is not the main reason feathers keep birds warm in most cases.
- Convection: This is the process by which heat is lost through the movement of air. Warm air around the bird rises, and as it moves away, it is replaced by cooler air, which draws heat from the bird’s body. Feathers trap a layer of air, which reduces the movement of air near the bird’s skin. This trapped air acts as an insulator, slowing down the heat loss by convection. This is the primary reason feathers help birds retain heat, as they significantly reduce the amount of warm air that escapes from the bird’s body into the surrounding environment.
In summary, feathers trap air, which reduces the heat loss by convection and helps keep the bird warm. This is especially important for maintaining thermal regulation in cold environments.