Ever wonder just how fast the wind is blowing outside? Or how humid it really is at your house? The following are some weather instruments that may come in handy if you want to be your own backyard meteorologist.
Anemometers measure wind speed. One of the simplest anemometer is made of rounded cups mounted the ends of four horizontal arms that rotate in a vertical shaft. When the wind blows, no matter which direction it’s blowing from, it catches in one of the four cups, pushing it around in circles. The speed of the wind is then measured by counting the number of times the cups rotate over a set time period of time.
Wind socks are another device that measures the wind. You often see wind socks at aiports. Wind socks reveal wind strength by the shape and movement of the sock. While this device won’t tell you the exact speed of the wind, it will give you an idea if the wind is heavy or light. Obviously if it’s flapping gently, the wind is light, but if the sock is straight out the wind is much strong.
Barometers measure the amount of pressure in the air, also known as barometric pressure. One kind of barometer uses mercury. The air pressure causes the mercury in the barometer to rise, providing a measure, according to the mercury’s height in inches, of the amount of pressure. Aneroid barometers which don’t contain mercury, are another popular type of barometer. These contain a small box inside, which changes shape when the air pressure increases, moving a needle connected to a numbered gauge. Normal air pressure readings range from 28 to 31. Rapid changes in air pressure often indicate that the weather is about to shift.
Psychrometers, also known as wet bulb thermometers, measure relative humidity. A psychrometer consists of two thermometers, one covered with a wet cloth, and one that is not. As the water evaporates from the cloth, the temperature on that thermometer decreases from the cooling effect. To find the relative humidity, compare the temperatures of the two thermometers on a special chart.
Rain gauges measure the amount of liquid precipitation. Any open container with a flat bottom and straight sides can be made into a rain gauge. Just use a ruler and a waterproof marker to add a scale of inches to one side and place it outside. Rain is the easiest form of precipitation to measure. Once a rainfall ends, simply look to see how many inches are in the container. To measure other kinds of precipitation, such as snow, you must first let it melt. Another good way to measure a deep snowfall is to use a ruler or yardstick. Every 10 inches of snow is equal to one inch of precipitation.
Weather vanes indicate the direction the wind is blowing. Incredibly simple to build, weather vanes include four directional markers, indication the points on the compass, and a rotating pointer. When the wind gusts, it pushes the arrow on the pointer, turning it to indicate the direction it’s blowing. Knowing which direction the wind is coming from can help you to predict whether a certain weather system is likely to move into your area. Winds from different directions often show specific characteristics that can help you predict the weather. For instance, winds blowing from the south are usually warmer and more humid than winds from the north.
A thermometer is also a must for weather buffs and amateurs alike!
Don’t want to buy all of this? Check out the Farmers’ Almanac‘s famous forecasting Weatherstick!