Environmental Engineering Reference
In-Depth Information
Figure 2.16
Energy transfers at the surface.
are picked up and blown along. Heat energy from the atmosphere is also transferred to
soils and plants through conduction and radiation (Figure 2.16).
HYDROLOGICAL TRANSFERS
Water similarly takes part in a variety of transfer processes (Figure 2.17). Water
condensing in the atmosphere releases latent heat; this warms the surrounding
atmosphere. Potential energy derived from the initial uplift of water vapour into the
atmosphere is transformed into kinetic energy as raindrops fall, and some of this kinetic
energy is transmitted to Earth's surface as rock and soil particles are splashed into
motion. Further potential energy is expended and converted to kinetic energy as the water
percolates through the soil, runs into streams and flows to the sea. The flowing water
again imparts some of its kinetic energy to material that it picks up and carries along.
The water also takes part in chemical processes of weathering and thus chemical
energy is transferred to heat energy, given off during the chemical reactions. In the sea,
the currents transfer energy laterally, while the upwelling and sinking of water masses
leads to vertical transfers. Finally the evaporation of water from the sea, from rivers and
lakes, and from the soil involves the conversion of thermal or radiant energy to kinetic
and potential energy as the water is again raised from its original position and carried to
higher levels in the atmosphere.
