Weather Station
The following information will help you to make more accurate weather forecasts:
Use of Weather Instruments:
The Thermometer:
Thermometers are used to measure exactly how hot or cold it is outside. Place the thermometer so it is protected from the direct rays of the sun. To get the extreme temperatures of the day, check the thermometer in the early morning hours and at mid-afternoon.
The Rain Gauge:
The rain gauge measures how much rain falls. Rainfall is measured by the depth of water that would lie on the ground if none of the rain escaped. Place your rain gauge out in the open. Measure the amount of liquid in the moisture which falls daily during your field study. Measure at the same time each day.
The Anemometer:
The anemometer is used to determine the wind speed in miles per hour. You may want to use the attached Weather Bureau Beaufort Scale.
The Psychrometer:
The psychrometer is used to determine relative humidity. The relative humidity is the percent of water vapor in the air at a given temperature as compared with the amount it could hold if it were saturated. For example, air with a 50% relative humidity in just "half full" of water vapor.
The psychrometer consists of a dry and wet bulb thermometer placed side-by-side.The relative humidity is determined by the difference between the dry and the wet thermometer. In order to accurately determine the relative humidity, you will need to use the relative humidity table.
The Wind Vane:
The wind vans is used to indicate the direction from which the wind in blowing, During your field study check the wind vane at about the same time each day.
Sky Coverage
In order for you to accurately forecast the weathere you will need to know something about the clouds. Clouds are sometimes referred to as "skywriters of weather." If you know about the clouds every cloud has a message which tells you something about it. The following cloud chart refers only to the main types within each cloud group:
Cloud Chart |
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| High Clouds: These clouds are composed of tiny ice crystals. Found at elevations of 20,000 to 40,000 feet. | ||
| Cirrus: thin, wispy, and feathery and are sometimes called "Mares' Tails" | Sky blue - fair Sky grayblue - Warm front |
|
| Cirrostratus:- thin and patchy, and are rarely seen. | Fair weather | |
| Cirrocumulus: - small, white flakes or globular masses that cause them to appear as ripples | Fair weather | |
| Middle Clouds: This family of clouds occurs from 6,000 to 20,000 feet above the earth, and they are either Stratus or Cumulus. | ||
| Allostratus:- dense veils or sheets of gray or blue. They look slightly striped. The sun looks as if it is being seen through frosted glass. | Warm front. Rain |
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| Altocumulus:- patches or layers of puffy or roll-like clouds--gray-whitish. | Possible weather change | |
| Low Clouds: This family ranges from near the earth to 6,500 feet in height. | ||
| Stratus:- low and like fog. Only a tiny drizzle can fall from these clouds. | Fine drizzles | |
| Nimbostratus:- true rain clouds. They have a wet look and often there are streaks of rain extending to the ground. | Rain | |
| Stratocumulus:- Odd shaped masses spreading out in a rolling or puffy layer. Gray with darker shadings. | Won't produce rain | |
| Towering Clouds: These clouds form at almost any altitude. | ||
| Cumulo-nimbus - are the thunderheads | "Thunderstorm cloud" | |
| Cumulus - puffy and cauliflowerlike. The shapes constantly change. | Fair weather cloud | |
BEAUFORT SCALE OF WIND FORCE |
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| Beaufort Number 0 |
Specifications for Use on Land Calm; smoke rises vertically |
Miles Per Hour Less than 1 |
U.S. Weather
Bureau |
| 1 | Direction of wind shown by smoke drift, but not by wind vanes. | 1-3 | Light |
| 2 | Wind felt on face; leaves rustle;ordinary vane moved by wind | 4-7 | Light |
| 3 | Leaves and small twigs in constant motion; wind extends light flag | 8-12 | Gentle |
| 4 | Raises dust and loose paper; small branches are moved | 13-18 | Moderate |
| 5 | Small trees in leaf begin to sway; created wavelets form on inland water | 19-24 | Fresh |
| 6 | Large branches in motion;
whistling heard in telegraph wires; umbrellas used with difficulty |
25-31 | Strong |
| 7 | Whole trees in motion; inconvenience felt in walking against wind | 32-38 | Strong |
| 8 | Breaks twigs off trees; generally impedes progress | 39-46 | Gale |
| 9 | Slight structural damage occurs.(Chimney pots and slates removed.) | 47-54 | Gale |
| 10 | Seldom experienced inland; trees uprooted; considerable structural damage occurs. | 55-63 | Whole Gale |
| 11 | Very rarely experienced; accompanied by widespread damage. | 64-75 | Whole Gale |
| 12 | . . . . . . . . . . . . . . . . . . | Above 75 | Hurricane |
From U. S. Department of Commerce, Weather Bureau