Question

Discuss how excess heat absorbed by Earth's low-latitude regions is transferred to heat-deficient higher latitudes through a process that uses water's latent heat of vaporization

Which one requires more heat enery, to melt 1 gram of ice or to evaporate 1 gram of water? Why?

Explain the difference between marine effect and continental effect on the climate. (Hint: consider the differences in heat capacity between water versus rocks).

Answer 1

1. Heat absorbed by the low latitudes of the Earth is transported to the higher latitudes via two mechanisms:

i) Atmospheric transport:

The air absorbs heat at the lower latitudes and rises up and moves to the higher latitudes. This air descends at about 30 degrees both north and south. The air descends as it loses its heat to the surrounding air at higher latitudes,. This air thus transports its heat to the higher latitudes. The major source of heat to the air is the heat absorbed by the water as it evaporates at the equatorial regions. This water vapor absorbs heat and evaporates when the heat absorbed is equal to the latent heat of vaporization. The water later condenses when the air in the surroundings absorbs the heat and the water vapor begins to condense. The air is mostly dry when it starts descending.

2. The latent heat of fusion for water i.e the heat required for ice to melt is 3.34x10⁵ J/kg, while the latent heat of vaporization i.e. the heat required to evaporate water is 2260 J/kg. Thus, more heat energy is required to melt water than is required to evaporate it (since latent heat of fusion for water is greater than the latent heat of evaporation).

3. The specific heat of water is greater than that of land. Thus, the continents heat and cool faster than the oceans. Thus, continents have larger climatic variations than land. This is why coastal regions have fewer variations in anuual temperatures than the inland regions