While it’s true that, according to the old saying, “everyone talks about the weather, but no one does anything about it,” you can study the weather and learn a lot about it. With a little knowledge and some basic tools, anyone can learn to do some simple weather prediction. Try assembling a home-made weather station using these tools, and see what you can learn about local weather. Keep a notebook of your daily weather readings and note the kind of weather you are having each day. What patterns can you see as you compare you readings to the weather?
BAROMETER
You’ll need a 1 liter plastic soda bottle, some clear tubing (the kind sold for aquarium pumps), some silicone sealer, clear packing tape, a sharp knife, and a permanent marker. Cut a hole in the side of the bottle near the bottom just large enough to insert the plastic tubing about 1/4 of an inch. Use plenty of silicone sealer to seal the hole shut. Tape the tube upright to the side of the bottle. Take the cap off of the bottle, and with your thumb over the top of the tube, fill the bottle nearly full. Put the cap on tightly and let go of the tubing. Cut the tubing so that the top of the tubing is below the surface of the water. Let the system rest so that it equilibrates. When the barometric pressure rises, air pressure will push the water down in the tubing. When pressure falls, the water level will rise. You can check the barometric pressure on weather websites such as weatherforyou.com to calibrate your barometer. A falling barometer (low pressure) often indicates rain or storms, while a rising barometer (high pressure) often means that the weather will clear.
NEPHOSCOPE
A nephoscope is an instrument for determining the wind direction high in the atmosphere. It’s a simple instrument made with a mirror and a sheet of paper. You’ll also need a compass, such as an orienteering compass, to find the directions. A metal mirror, such as the kind you find with the camping equipment at a sporting goods store, works well. Cut a circular hole in a sheet of paper that will fit over the mirror. Tape the mirror to the back of the hole. Mark the cardinal points around the hole: North, East, South, and West. Also mark Northeast, Northwest, Southeast, and Southwest. Lay the nephoscope flat on the ground. Use the compass to align it so that the mark for “north” is facing north. Look into the mirror and watch any cloud movement that passes over it. Note what direction the clouds are moving. If, for example, the clouds move from the northeast to the southwest, then the wind is a northeast wind. You may see that clouds at different altitudes move in different directions. Keep track of what you see, and what kind of weather is associated with different wind directions.
WET AND DRY BULB (TEMPERATURE AND RELATIVE HUMIDITY)
Get two inexpensive bulb-type thermometers. Mount them both on a board, and cover the bulb of one with some cotton wick, a piece of cotton shoelace, or something similar. Wet the cotton and fan it with a piece of folded paper, which causes evaporative cooling to take place. When the liquid in the thermometer stops falling, read the temperature on both thermometers. The difference between the two thermometers is used to determine the relative humidity. You’ll need a table to convert your data into relative humidity. The National Oceanographic and Atmospheric Administration publishes a good one:
http://www.wrh.noaa.gov/sew/fire/olm/temp_rh.htm
RAIN GAUGE
A simple glass jar can be used to measure the amount of rain that has fallen. Use clear silicon glue to glue a six-inch ruler to the side of the jar with 0 aligned to the bottom of the jar. Find an empty can, such as a tuna or cat food can, that will hold the jar comfortably. Fasten the can to a tall wooden stake and drive the stake into the ground in your yard where it is well away from trees, roofs, or other structures that will interfere with rainfall. Place the jar in the can. You can add a collar of wire to keep the jar in place. After each rainfall, check the level of water in the jar, and dump it out.
Here are websites for more weather instruments you can make to improve your weather station:
Barometers:
http://www.homelyscientist.com/2006/10/09/make-your-own-barometer/
http://www.salemclock.com/weather/weatherglass.htm
http://www.salemclock.com/weather/jarbar.htm
Hygrometer (another instrument for measuring relative humidity)
http://www.salemclock.com/weather/hygrometers.htm
http://www.sciencebuddies.org/science-fair-projects/project_ideas/Weather_p010.shtml
Anemometer (for measuring wind speed)
http://www.worsleyschool.net/science/files/anemometer/anemometer.html
http://www.salemclock.com/weather/anemometers.htm
Weather vane (for determining wind direction at ground level)
http://www.salemclock.com/weather/windvane.htm
