Hobbies And Interests
Measuring Pressure
Weather Instruments that measure atmospheric pressure are barometers. Atmospheric pressure is an indicator of potential storm systems moving into or out of your area. There are two kinds of barometers, mercury and aneroid barometers. A mercury barometer has a glass tube that holds a column of mercury. As a low-pressure system moves into the area, the mercury in the tube begins to fall, indicating that a storm is on the way. When the storm ,or low-pressure system, leaves the area, the mercury in the tube will rise. An aneroid barometer does not use liquids, but rather a system of springs and bellows that expand and contract with changing atmospheric pressure. An aneroid barometer is a far more sophisticated instrument, measuring pressure changes down to the minute.
Measuring Rainfall
Weather instruments that measure rain and snowfall are rain gauges. The most basic rain gauge is a graduated cylinder, or tube, that collects water, measuring rainfall in millimeters, centimeters or inches. A tipping bucket rain gauge consists of a graduated cylinder that balances on two levels. Once the cylinder is full, it tips over and empties into a container that measures the amount of precipitation collected. Similarly, a weighing rain gauge collects water in a container and then measures the weight to gauge the amount of rainfall over a given period.
Temperature and Wind Instruments
A thermometer, which is a sensor in contact with the air, measures temperatures in both Fahrenheit and Celsius. To get the most accurate reading, the National Weather Service places its thermometers in special boxes, elevated 6 feet off the ground. The boxes shield the thermometer from the rays of the sun to get a more accurate reading. An anemometer is an instrument with speed sensors that measure wind velocity. Conversely, a wind vane is an instrument used to determine wind direction.
Measuring Moisture
A hygrometer is an instrument for measuring the presence of water in the atmosphere, thereby determining humidity. Hygrometers consist of wet and dry bulb thermometers that measure temperature changes and moisture. The wet bulb detects the point at which water evaporates when the temperature drops, as the temperature of the dry bulb gradually increases. This calculates humidity based on the temperature difference between the dry and wet bulb. There are also dew point hygrometers, which are instruments that measure the moisture in the atmosphere once the air reaches saturation.