Weather Tools 6.4.5 Use appropriate instruments and tools to collect weather data (including wind speed and direction, air temperature, humidity, and air pressure. ? Essential Question What weather instruments and tools do scientists use to measure weather and how do they work? Anemometer Measures the wind speed in miles per hour. To use it, count the number of rotations in one minute (rpm). You can then convert that to miles per hour. That’s a complex formula. ;) Wind Vane A tool used to measure wind direction. Sometimes referred to as a wind-weather vane or a wind sock. Wind direction is described by the direction from which the wind is blowing as indicated by the pointer. Sling Psychrometer A two-thermometer instrument also referred to as a wet-dry bulb; Used to measure the relative humidity (the amount of water vapor in the air). Temperature readings are converted using a relative humidity table. How do I use it? Find the dry bulb reading. 2. Find the wet bulb reading. 3. Subtract the wet bulb from the dry bulb. (Difference) 4. Use the chart to calculate the relative humidity. 1. Practice using a sling psychrometer. 1. Use the following table. Trial # 1 2 3 4 5 6 7 8 9 10 Dry Bulb Wet Bulb Difference b/w Humidity Trial #1 Dry Bulb Wet Bulb Trial #2 Dry Bulb Wet Bulb Trial #3 Dry Bulb Wet Bulb Trial #4 Dry Bulb Wet Bulb Trial #5 Dry Bulb Wet Bulb Trial # 6 Dry Bulb Wet Bulb Trial # 7 Dry Bulb Wet Bulb Trial # 8 Dry Bulb Wet Bulb Trial # 9 Dry Bulb Wet Bulb Trial # 10 Dry Bulb Wet Bulb What do you notice about the relationship between the readings and the humidity? Barometer Measures the air pressure in inches of mercury or millibars (mb) There are two pointers: The one inside the glass is the current reading and it moves according to the air pressure. The one on top is the set pointer. You move it so you will know tomorrow what the setting was today. Using the Barometer Find the current reading. That would be the full arrow. 2. Read the set pointer. That would be the half arrow. 3. Compare the current reading to the set pointer 1. If the current reading is higher, then the air pressure is rising indicating fairer weather on the way. If the current reading is lower, then the air pressure is falling indicating rainy conditions may be coming. https://www.youtube.com/watch?v=i2UKTpIQG6M Thermometer A tool used to measure air temperature in degrees Fahrenheit or Celsius. To determine the temperature, read to the highest mark on the scale as indicated by the red dye. Rain Gauge A tool used for measuring the amount of precipitation in inches or centimeters. Using the Rain Gauge Rain gauges work just like a graduated cylinder, so measure to the meniscus (the dipped portion).