Humidity
Humidity is caused by water which evaporates from the oceans, rivers, and lakes and turns into an invisible vapor which is added to the blanket of air surrounding earth. High and low humidity is determined by the quantity of water in the air on a given day. The humidity is said to be at one hundred percent when the air is holding as much water as it can for the temperature. It is the water in the air that makes a person feel “sticky”.
Dew Point
The dew point is reached when the air is holding as much water as it can.
The water vapor found in the atmosphere condenses and forms drops of water which settle on the grass, trees, and flowers. The temperature that the air must meet before it squeezes out the water is the dew point.
Frost
Frost is tiny bits of ice formed when the temperature of the air is below freezing. The objects upon which frost forms must also have a temperature at or below the freezing point.
Clouds
When warm air rises and cools and is holding all the moisture it can, the dew point has been met and the air must squeeze out the excess water.
These water vapors condense on dust found in air and the two combine to form droplets. Millions of these water droplets unite to form clouds.
The most common types of clouds are the cirrus, cumulus, nimbus, and stratus.
Cirrus Clouds
Cirrus clouds are thin clouds which curl up at one end. The word, cirrus, means to “curl”. These clouds, the highest in the sky, are formed from ice crystals. These clouds are the highest in the sky, sometimes obtaining a height of four to ten miles above the surface of the earth. The height may give the clouds the appearance of being very slow moving when in actually they move very swiftly across the sky. Cirrus clouds in the sky may be an indicator of an oncoming storm.
Cumulus Clouds
The “heap” or “piles” of clouds most frequently seen in the sky are the cumulus clouds. These clouds form as the result of warm moist air cooling as it rises high into the air, creating the white, puffy heaps associated with this cloud. As the sun sets, the cumulus clouds disappear for they no longer have the warm air rising from the ground to sustain the cloud. Rain showers frequently fall from cumulus clouds.
Nimbus Clouds
Nimbus clouds are thick and shapeless and their appearance in the sky are considered to be the forebearers of rain or snow.
Stratus Clouds
The stratus cloud hovers close to the ground and are actually white sheets of high fog. As the sun’s warmth reaches the earth these clouds usually disappear to display a clear, blue sky.