Exercises (b)

1. Establish compliance between parts of sentences:

1. when the rate of precipitation exceeds 1. as infiltration will percolate

the rate at which water may infiltrate into the ground

into the soil

2. this part of the precipitation after 2. a level which is completely

filling the surface depressions saturated

3. there is some loss in transit because of 3. surface runoff usually

evaporation to the atmosphere occurs

4. a portion of the precipitation 4. where it may be confined by

penetrating the ground surface tighter soils and thus subjected

5. if not absorbed by soil deficient to pressure

in moisture, this water eventually reaches 5. finds its way over the surface

6. ground water may also flow through of the ground

porous strata and reach a level 6. and infiltration to the bottom

and sides of a definite

stream channel

Text (b

Read the text « Evaporation and Transpiration, using a dictionary:

Moisture exists in all three states of matter in the atmosphere, as vapour, liquid, or solid; changes from one to the other are known as phase changes, and significant amounts of energy are involved in accomplishing these changes. In the process of evaporation, 600 calories of latent heat are required to change one gram of water from a liquid to a vapour state. Normally such a heat loss would be quickly compensated by conduction and radiation. In the reverse process of condensation, latent heat is released into the atmosphere, causing a slight rise in temperature.

Water in the liquid state, when sufficiently subjected to heating by solar energy or otherwise, passes into the gaseous state. This phenomenon is called «evaporation».

Of the total precipitation, a very large proportion falls directly upon the oceans, large inland lakes, and other water surfaces such as rivers and ponds. That falling on the ocean, together with the water returned as runoff, maintains the equilibrium evidenced by the substantially constant sea elevation. Parts of this precipitation on water surfaces are ultimately evaporated into the atmosphere and become part of the atmospheric moisture. In the Arctic and in the northern areas of the temperate zones, evaporation from water and snow surfaces is frequently less than the precipitation, but the surplus in ultimately discharged to the oceans from which it is evaporated. Elsewhere, evaporation from water surfaces is generally equal to or greater than the precipitation falling on them.

One of the basic functions in the life processes of vegetation involves the process of taking water from the soil through the roots, utilizing it in producing growth and maintaining life, and discharging it from pores into the atmosphere as water vapour. This process of returning soil moisture to the atmosphere is called «transpiration». The amount of precipitation thus returned varies greatly with the character of vegetation and the moisture available to the root system of the plants.