Humidity and wind are the easiest weather forces to measure.
Making weather instruments from household items is an inexpensive and exciting science project for kids. It allows children to manipulate and interpret weather events that otherwise seem mysterious. Working with the weather gives young children an opportunity to engage in inquiry-based learning, establishing a hypothesis and using homemade weather instruments to test their predictions. Weather instruments can be made and used one at a time, or made together and used in conjunction as a weather station.
Rain Gauge
Make a rain gauge from an empty plastic container. Use a permanent marker to mark the side of the container. Draw and label a mark every 1/2 or 1/2 inch all the way up the side of the container. The most important thing to remember when selecting a container to use as a rain gauge is that it must have a flat bottom and straight, vertical sides to be accurate. The general shape of the container does not matter. It can be round or square, as long as it has a consistent diameter. Do not use something like a pop bottle or sour cream container that has a telescoping or hour-glass shape.
Wind Sock
Wind socks show what direction the wind is blowing and changes in the wind's direction. Make a wind sock by taking the lid off a round cardboard oatmeal container and cutting off the bottom so you have a hollow tube. Decorate the tube with construction paper, contact paper, stickers, glitter and other craft supplies. Glue or tape crepe paper streamers around the bottom of the tube to create tails around the base of the sock. Punch two holes in the top edge of the tube and tie a long ribbon between them to serve as a hanger. Hang the sock from a tree branch, porch rail or post. The less sheltered the hanging location, the more accurate the sock's movements will be in relation to the wind's actual direction and strength.
Barometer
To make your own barometer, which measures atmospheric pressure, stretch a latex party balloon over the top of a quart mason jar. A wide-mouth jar is preferable to a narrow mouth. Stretch the party balloon over the jar's mouth so that is creates a hard, flat surface, like the top of a drum. Put a strong rubber band over the mouth of the jar and the neck of the balloon to secure its position. Tape a straight pin to the end of a drinking straw. Glue the opposite end of the straw to the center of the balloon, so that the straw lays horizontally across the balloon's surface. The straw and the side of the jar should meet at a 90 degree angle. Read the homemade barometer at the same time every day for the most accurate results. When pressure is high the balloon will sink down into the open mouth of the jar and the straw will point upward more, and when pressure is low the balloon will swell and the straw will point down. Use a ruler to measure the number of inches from the surface on which the jar is set to the straw. Record the measurement daily to track patterns and trends in local barometric pressure.
Hygrometer
Find a section of 2-by-4 inch lumber between 9 and 12 inches long. Cut a large triangle or arrowhead shape from a plastic container lid. Tape a dime to the plastic arrow near its point. Punch a finishing nail through the center of the triangle's base. Enlarge the hole around the nail until the pointer spins freely around the nail. Glue three long strands of human hair to the center of the arrow. Hammer the finishing nail into the 2-by-4, about 1 inch up from the base. Nail a second finishing nail 1 inch down from the top of the 2-by-4, directly parallel to the nail in the pointer. Pull the three strands of hair up to the top nail and glue them in place. The hair must be pulled tight so that the arrow is pointing horizontally for the hygrometer to operate properly. The human hair follicles react to the moisture in the air by expanding and contracting. When the air contains more moisture, the hair follicles lengthen and the arrow points down. When the air is drier, the hair follicles contract and the arrow points up. Take note of the arrow's position daily. Use a ruler to measure the rise or fall of the arrow from its center or level point.
Tags: finishing nail, hair follicles, around nail, arrow points, balloon over