Question

In which one of the following habitats does the diurnal temperatures of the soil surface vary most?
A. Forest
B. Desert
C. Grassland
D. Shrub land

Answer 1

Hint: Diurnal refers to the change of temperature from the daytime high to the nighttime low. This begins each morning when the sun rises and its rays extend toward and strike the earth’s surface.

Complete answer:
Solar radiation directly heats the ground, but because of land’s high heat capacity the ground doesn’t immediately warm. As the ground’s temperature warms it heats a layer of air directly above it by conduction. At noon, sunlight is at its most concentrated strength . Afternoon the sun begins its retreat across the sky. From this time until sunset ,the intensity of incoming solar radiation continually declines. When more heat energy is being lost than the incoming energy at the surface, a minimum temperature is reached i.e at night. On any given day, the temperature variation from low to high temperature is roughly 20 F to 30 .Heat conductivity of soil increases in direct proportion to its moisture content.
The variation in temperature of forests is less as compared to other areas because the whole surface is covered with shadow of trees. So, this option is not correct.
Deserts have very hot days and very cold nights. Due to bare plant cover, the soil of desert is much more exposed to these fluctuations as compared to that of other areas. During day time, the soil becomes hot and at night it frequently cools down. Therefore, this option is correct as here temperature varies most.
Grasslands have less variation as compared to other areas. So, this option is incorrect.

Shrub land is covered with shrubs so here the variation is less i.e the temperature of soil at day and night does not vary much. So, the option is incorrect.

Note:
Humidity of air affects the diurnal range of temperature in an effective manner. Lesser the amount of water vapour in the air, greater the amount of heat lost. On the other hand, large amounts of water vapour in the air absorbs a large heat from the earth's surface and minimizes the decrease in temperature.