Air Moisture Science Project Idea

How Moisture Gets into the Air

Evaporation

It is evident that there must be considerable water in the air, in the form of invisible vapor. It has been estimated that if all the moisture in the air were condensed into water, it would make a layer of about one inch in depth over the entire surface of the earth. Some very common observations will indicate to us how this water gets into the air.

(1) What happens to wet clothes hung in the air?

(2) On what kind of days do they dry best?

(3) Do they dry better during day or night?

(4) What becomes of the rain puddles that are formed on the streets? Does the temperature seem to make any difference?

(5) What happens to a shallow pan of water left standing for a number of days?

(6) What must be added to a balanced aquarium from time to time?

(7) Will frozen clothes, hanging on a line, dry?

(8) What happens to water that falls on soil, as in a cultivated garden or field?

(9) After a number of dry days, compare the moisture of soil under a board or stone with that of the surrounding soil. During very dry weather in summer, almost the only place one can find earthworms is under boards, logs, or stones. How do you explain this?

(10) When barrels are left empty they often fall to pieces. Why?

(11) In dry weather, farmers sometimes pour water around the rims of the wheels of their wagons. Why?

(12) How do leaves appear after having been removed from a plant?

From these observations we must conclude that objects containing water give it off to the air. The changing of the water into a vapor is called evaporation, the reverse of condensation which we considered in the formation of dew, clouds, and rain. From your observations, state the conditions which you think would affect the rapidity of evaporation. Not only are objects on the land giving off water in the form of vapor, but also the surfaces of all bodies of water, rivers, lakes, and oceans. This water, in an invisible form as vapor, is changed back into visible forms as dew, clouds, rain, and snow.

When water evaporates, substances dissolved in the water remain behind. This may be illustrated by allowing a vessel of water in which has been dissolved some soda or salt to stand exposed to the air until the water has evaporated. Water in streams flowing to the ocean contains some soluble mineral material taken from the earth, through which the water has trickled. What happens to this mineral material when the water evaporates State in your own language, what you consider to be the cause of the saltness of the ocean. Endeavor to find out why the Great Salt Lake contains salt water, and the Great Lakes, fresh water.