Introduction: (Initial Observation)
Weather affects our everyday lives. We dress and plan our day according to the weather. This means that it is important that our weather forecasters are accurate when predicting the weather. Instruments such as thermometers and barometers give readings of the temperature and air pressure, which then generally give us an idea of what the weather is going to be like. Throughout the day, temperature and air pressure rapidly change, and a meteorologist cannot spend his or her whole day observing thermometers and barometers waiting to record the change in temperature or air pressure. For this reason, these instruments need to record the changes in temperature and air pressure automatically.
Weather records can be any weather data such as temperature, air pressure, wind speed, precipitation, etc. It is not too difficult to obtain weather records in today’s world. All the technology from computers and the internet have made everything so much easier. You can find the weather of any place at anytime.
If you want the changes of temperature of a location for a certain period of time, you can use a computer program that is hooked up to a digital thermometer. This is called a thermograph program. A thermograph is a instrument that records changes in temperature on a chart.
In a computerized thermograph, the digital thermometer will find the temperature and record the data into the computer in the time intervals set by the user, which in most cases is the meteorologist.
The computer program can then give a chart of all the temperatures and the temperature changes. By having the chart of all the data, you can know the current temperature, the days highest temperature, and the days lowest temperature.
Today’s technology makes it easy to record changes in the weather, however, it was not always this easy. In the past, thermographs were used to record temperature change, however, they were not digital or computerized. Old fashioned thermographs consist of two metals of different alloys, such as steel and iron, which are welded together in a coiled form. The difference in the coefficient of expansions will uncoil or tighten the coil when subjected to temperature changes. The movement is then magnified by a lever system to a horizontal pen which is attached to the coil with a pen nib slightly rested on a chart. The scaled chart is wrapped around a drum. A clock is build inside the drum. As the clock rotates the drum, the pen records the temperature on the scale, therefore, resulting in a graph or chart which shows temperature change.
Another important weather instrument is the barometer.
Just like you can weigh yourself, you can weigh air. The weight of air is called air pressure. A barometer measures the weight of the air on one little area. This tells us the pressure of the air around us. The markings on a barometer are called “inches of mercury.” By reading these markings, meteorologists can tell if the air pressure is more or less. Meteorologists use this to let us know when the weather is going to change
There are several types of barometers. In 1642, a scientist in Italy invented the Mercury barometer. The Mercury barometer is still used today. It has a glass tube filled with liquid mercury. The barometer tube that holds the mercury is made of glass. It is almost three feet tall and is open on one end. The tube is tipped upside down and placed in a container filled with more mercury. The weight of the air presses on the open end of the tube. The mercury acts like a balance. It balances the mercury in the tube with the mercury out of the tube. By reading the “inches of mercury” marks on the side of the glass tube, we can know the pressure of the air. If the air pressure increases, the mercury goes higher in the tube. If the air pressure decreases, the mercury goes down in the tube.
Another kind of barometer is the aneroid barometer. This is the most common type of barometer for home use. The aneroid barometer doesn’t use mercury. It has an aneroid cell. The aneroid cell volume is very sensitive to changes in atmospheric pressure. The cell volume gets smaller as the atmospheric pressure increases.
Just like a thermograph measures temperature change, a barograph measures and records the change in air pressure. It has a pen attached to it. The barograph is used by meteorologist to record air pressure change.
Thermometers and barometers measure temperature and air pressure. However, how can we use these instruments to record the changes in the temperature or air pressure automatically?
The purpose of this project is to attempt to build a mechanism to record one of the weather conditions such as temperature or air pressure automatically.
There are many variables that can possibly affect the function of an automatic recording device. Among these variables are the method of measurement, friction, speed, and sampling rate (per minute, per hour, per day). However, in this project we are not focusing on studying any specific variable. We will just try to make any workable combination to do the job of recording the data automatically.
Both air pressure and temperature can cause expansion and contraction of air. My hypothesis is that we can use a can of air with a rubber diaphragm to measure and record such changes. This device can be used as a thermometer where air pressure is fixed. It can also be used as a barometer where temperature is fixed.
The second part of my hypothesis is that we can use a regular mechanical clock to build a recording device.
We will be creating our own automatic weather recording device. The device that we will make can either measure the temperature or air pressure.
* To measure the air pressure, we should use the device in a certain temperature or make necessary adjustments based on the temperature change.
1. Start by opening the clock. Open the screws in the back. Open and remove the keys. Now you should be able to remove the back panel of the clock and see the the clock movement. A clock movement is the part of the clock that has all the gearing in it. The movement is also called
the “clockworks” or the clock “inners” or the “motor”. They all just mean the part of the clock that is doing the work, the two brass plates with all the gears in it.
Now remove the bells and legs. This will also release the motor, so you can remove the motor with dial and handles attached.
You will not need handles too, so pull the up and remove them.
Now you need to secure this bare clock to a base board,
You can do it in many different ways, but we have used another sheet of metal that is connected to the clock from one side by screws and connected to the board by some other screws. It is not a perfect design but it works.
2. Measure and cut out a circular sheet of metal about 6 inches in diameter. Cut a whole in the middle of the sheet of metal. Remove the hands from the clock (if you have not done it yet!). Insert the sheet of metal where the clock hand used to be. This will cause the piece of metal to rotate slowly by the hour just like the hour hand does on a clock.
3. Cut out a piece of paper the same size as the sheet of metal. Label 12:00, 3:00, 6:00, and 9:00 on the circle in the appropriate locations. Now, attach this to the sheet of metal using small pieces of adhesive tape.
4. Take an empty metal can and cover it up with a flat piece of rubber from a balloon or latex glove. Do this by extensively stretching the balloon or latex glove and then placing it over the opening of the can. Use rubber bands or a string to secure the balloon or latex glove on the can.
5. Take a balsa wood or Popsicle stick. The measurements of the wood should be around 8″ to 13″ in length and about an inch in width. If your piece of wood is not near these dimensions, make the necessary changes . Attach the wood to the center of the can by taping it to the balloon or latex glove. Use a another piece of tape to secure the wood to the top of the can close to the edge.
The balsa wood that we used was very flexible. So we cut two longs strips and glued them to each other like you see in the picture. That made it light and rigid.
6. Place a pencil tip on the end of the wood just like shown in the picture below. Use tape to secure the pencil tip to the wood.
The can with the balsa wood and pencil should look something like this
7. Finally, place the can and clock next to each other like shown in the pictures below and test your instrument.
* The following are pictures how to setup the can and clock. This is the finished product.
Materials and Equipment:
1. Metal Can
2. Thin sheet of metal (about 10″ x 10″)
3. Large, durable balloon or latex glove
4. One foot long piece of balsa wood, or a two Popsicle sticks
5. Electrical Tape
6. A mechanical alarm clock
7. Paper and a pencil
Results of Experiment (Observation):
The device that we created measured the temperature and air pressure change within a 24 hour period. It also automatically recorded the data. When we used the instrument to measure air pressure, we sealed it off with Styrofoam since it is a very good insulator. We had to insulate it so that the temperature inside the can would stay steady and not change due to outside temperature change. We made our device in intervals of 1 hour and the circle was in the form of a clock, so it recorded 24 hours of either the temperature or air pressure. After 24 hours, you need to put a new piece of paper to record the data.
This project did not have any calculations, however, if you do any calculations while doing this project, include them in this section of your project.
Summary of Results:
We tested the device that we created for three days. Since the paper makes one full rotation every twenty-four hours, we changed the paper at the same time every day. The results of the day where ready for us when we went to change the paper. We did have some problems with the pencil since the lines came out very light. A marker can be used to fix this problem, however, the marker has its own problems. The marker smears and is too heavy to put on the balsa wood. For these reasons, we decided to go with the pencil even though the lines weren’t very visible.
Anytime you automate a process, it makes life much easier. Automations save time, save money, and give better results. Our “weather recorder” that we created made recording a full days temperature or air pressure very easy. The only manual part is changing the paper on the machine every day to record the data, which takes a couple of seconds.
Overall, the experiment was a success.
Some of the problems and errors that I noticed are as follows:
- The way that I mounted the pencil makes it move on a curve. So at some points it may not touch the graph paper. One solution is mounting the pencil faced to the left or right. (Vertical to it’s current orientation). The other solution is mounting s spring behind the pencil, so the pencil will be able to slide back and fourth if needed.
Additional experiments related to weather instruments
- Glass barometer tube 36″ long, closed at one end
- Small glass or beaker
- Mercury or colored water
- Ring stand with clamp
- Cardboard strip, 2″ x 10″
- Scotch or masking tape
Pour the mercury into the barometer tube, filling it completely. Pour the remaining mercury into a beaker. Place a finger over the open end of the tube and invert the tube, lowering it carefully into the beaker containing the remainder of the mercury. Clamp the tube upright on the stand.
Mark a scale of inches and half inches on the cardboard, and label it from 24 to 36 inches. With the yardstick, measure the actual height of the mercury column and attach the scale to the proper spot on the tube.
Watch the day-to-day variations in the height of the mercury. Record your readings. Compare them with radio and newspaper reports of local barometric pressure conditions.
NOTE: Be very careful that the mercury does not come in
contact with any jewelry you may be wearing.
- Empty milk carton
- Large sewing needle
- Broom straw, 2″ long
- Scotch or masking tape
- 9″ human hair, wiped clean of oil
- 4 thumbtacks
- Paper clip
Cut the carton so as to make a small horizontal slit near the top; insert the paper clip. (Fig.1) Cut a vertical slit near the bottom. Then cut horizontal slits perpendicular to this cut at its end points – like an H on its side. (Fig.1)
Pry out the flaps thus made and bend them to an upright position. Insert the needle through these flaps. (Fig.2)
Tie the hair to the paper clip, wind it around the needle, tape the penny to the other end of the hair, and let the penny hang over the end of the box, which should be lying on its side.
Put a card with a scale on the side of the carton under the straw which has been pushed through the eye of the needle. (Fig.3)
Place the hygrometer on a wet towel in a dishpan and cover with a damp cloth. After 15 minutes remove it from the cloth and set the straw at numeral 10 on the scale. Watch to see whether the straw moves.
Since humid air causes the hair to stretch and dry air causes it to shrink, the straw should move toward the dry end of the scale as the hair dries.
- Thin sheets of aluminum (cardboard)
- Dowel stock
- 2 glass beads
- 2 thin wooden sticks, 18″ x ½”
- Aluminum solder
The cups of the anemometer are made from the aluminum. Cut 2 circles about 4″ in diameter. Cut these circles in half along the diagonal. Join the straight edges with aluminum solder, malting 4 small cups.
Attach the cups to 2 crossed sticks, so that all are heading in the same direction, as illustrated. Join sticks to dowel stock as follows: Nail, bead, crossed sticks, bead, dowel stock. Beads will act as bearings so the wind will turn anemometer freely.
Note that spinning is faster as the force of the wind increases.
- Glass bottle, 1-pint size
- Rubber stopper with 1 hole
- Glass tubing to fit hole, 24″ long
- Dye or colored ink
- Sealing wax or paraffin
- Scotch or masking tape
- Cardboard strip, 10″ x 2′
- Ordinary thermometer
Place the glass tubing, sealed at one end, through the stopper. Fill the tube full of water colored with the dye. Quickly invert the tube, placing the lower end in a bottle about one-fourth full of the colored water. Press the stopper firmly in the bottle. Adjust the liquid in the tube by loosening the stopper or pressing it further into the bottle until the liquid is about half way along the exposed portion of the tube above the stopper. Then use the wax to seal the tube in the stopper and the stopper in the bottle. Tape the cardboard to the tube above the stopper.
Note the temperature on an accurate thermometer. Record this temperature on the cardboard, which will act as a temperature scale. Place the thermometers in a different temperature situation and leave them for a few minutes to allow the thermometers to register the new temperature. Note the new reading and mark on the scale. Carefully measure the distance between the two readings on the scale, and mark other degrees of temperature on it, as all other changes will be in the same proportion.
Push a pin through a drinking straw and into a vertical slab of wood – a cork notice board is ideal. The straw should pivot very easily on the pin.
Take a long human hair, the longer the better, (I designed this in the late ’60s when we all had long hair) and tie it to a drinking straw as shown. The pivot should have been placed so that the hair is kept under slight tension.
Tie the other end of the hair to another pin stuck into the notice board.
Place the contraption in your kitchen. The hair will lengthen and the straw “indicator” will move when you boil a kettle and the humidity rises.