How to Read Weather Instruments

Reading a thermometer during a sunny day at the beach will tell you the temperature.

Weather is around us all the time, and asking about it is one of the most benign ways to start a conversation. Even though weather is a daily part of our life, we often don't know how to measure its effects. If it's hot outside, you can find the temperature by reading a weather instrument. If it's windy, you can find the direction of a wind by reading a weather instrument. With some basic guides, you can read some common weather instruments and have some scientific measurements of the weather for the day.

Things You'll Need

• Wind vane
• Compass
• Thermometer
• Barometer

Instructions

1. 

   A wind vane is a weather instrument that gives the direction of the wind.

   Observe the wind vane. Find the wind vane's pointer. The pointer has a sharp pointed end that looks like an arrowhead, and a flat end that looks like a fin. The flat end of the pointer is pushed by the wind and the pointer turns in the direction the wind is coming from. The wind vane essentially points in the direction of the wind. Note the direction of the pointer with either the compass rose attached to the vane or your own hand-held compass. You have now read the weather vane, and you have determined the direction of the wind.

2. 

   A thermometer is a weather instrument that measures the temperature.

   Look at your thermometer. Note where the red mercury has risen along the inside of the glass tube in the middle. Look to the numbers charted alongside the glass tube. These numbers tell you the temperature in degrees of Fahrenheit or Celsius. Note the number that is next to the highest point of the red mercury in the glass tube. This number is your temperature reading.

3. 

   A barometer is a weather instrument used to measure air pressure.

   Look at your barometer. You will see a long tube and a shorter tube that are filled with mercury. Note the levels of the mercury in both tubes by noting the numbers next to the tube. You will need to note the initial levels so you can determine if the air pressure is going up or down throughout the day. As the air pressure surrounding the tubes increases, it will force air into the smaller tube. The mercury will go down in the smaller tube and up in the larger tube. Throughout the day, periodically check on the levels of mercury in the tubes. If the levels in your long tube are lower then your starting level, then the air pressure went down. If the levels in your long tube are higher then your starting level, then the air pressure went up.

Tips & Warnings

• Mercury used in many weather instruments is poisonous. If the glass tubes containing mercury in any of your weather instruments break, immediately wash your hands and exposed skin. Wear protective gloves and dispose of the broken instrument immediately.

References

• USA Today: How a Barometer Measures Air Pressure
• Understanding Wind Direction and Making a Weather Vane
• Reach Out Michigan: How to Read a Thermometer

Resources

• Weather Forecasting