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Science Project Ideas:
You can use an infrared thermometer to learn much about the sky and various kinds of clouds. These experiments can be done at any time of the day or night. Always use care when using an infrared thermometer outdoors, in public places and around strangers who may be unfamiliar with what you are doing. Be careful to avoid touching objects that are so hot they might burn you. Here are some projects you can try:
1. Measure Sky and Cloud Temperature with an IR Thermometer.
The apparent temperature of the sky measured by an infrared thermometer provides basic information about the greenhouse effect.
Warning: Never point a laser pointer at a person, car, truck or airplane!
Project: Go outdoors and point an IR thermometer straight up at the open sky and write the time and temperature in a notebook. Repeat this procedure for a cloud that is overhead or nearly so.
What did you observe? What was the difference in the sky and cloud temperature?
Repeat your measurements at various angles around the sky. What happens to the temperature as you point the IR thermometer closer to the ground?
If the infrared thermometer is equipped with a laser pointer, be sure to switch it off during this experiment.
2. Investigate Cloud Temperature with an IR Thermometer.
The dew point is the temperature at which water vapor in the air condenses as moisture. Morning dew on grass means that the night time temperature fell to or below the dew point. Fog means the temperature of the air is at the dew point. When warm air loaded with water vapor rises in the sky, it cools and condenses into clouds when the temperature of the air falls to the dew point.
Project: Is there a relationship between the the dew point and the temperature of the bottom of cumulus clouds measured with an infrared thermometer? The temperature of cumulus clouds measured for this project was very close to the dew point. What are your results? To find out, measure the temperature of overhead cumulus clouds once a day for at least 10 days. On days when you measure clouds, check with your local US Weather Service office to find the dew point. Enter your data into a computer spreadsheet and make a graph to compare the dew point and the cloud temperature. You can go further by making a scatter graph and selecting the trendline feature. Then select the R squared function to determine the degree of agreement between your cloud measurements and the dew point. The closer the R2 is to 1, the better the agreement.
Going Further: Does this method work with fog? Does it work with clouds other than cumulus clouds?
More Going Further: You can estimate the altitude of the base of cumulus clouds at this cloud base calculator.
3. Graph the Temperature of the Sky Overhead.
The Background section above describes apparent sky and cloud temperature measurements made from South-Central Texas on September 21, 2008, and the temperature measured by a weather balloon launched from Del Rio, Texas, the same day. The graph below shows the temperature measured by the weather balloon from the ground to the upper troposphere when an infrared thermometer indicated a sky temperature just above freezing (34 degrees or 1 degree C).
 Click to view enlarged version.
Project: You can make similar graphs for your sky measurements. Here's how:
Ideally, measure the apparent sky temperature within an hour or two before or after a weather balloon flight. Weather balloons are launched from weather stations around the world at 0 Zulu and 12 Zulu. "Zulu" means Coordinated Universal Time (UTC). UTC is the same time everywhere on Earth. Thus, when it is 10:30 UTC in Colorado, it's 10:30 UTC in Australia. You can find the UTC for your location by clicking here. You will see the graphic below:
 Click to view enlarged version.
Notice the list of places below the map (Samoa, Hawaii-Aleutian, etc.) To find the UTC, click on "UTC" at the end of this list. To find your local time, click on your time zone. By finding your local time and UTC, you can determine how to convert your local time into UTC. For example, when the UTC is 12:00 hours, in the Central Time Zone (light blue central States in the map above) the local time is 06:00 AM. This means that the UTC is Central Standard Time - 6 hours. For Daylight Saving Time, the UTC is Central Daylight Time - 5 hours. The Navy has posted an online table here that converts the main US time zones (Pacific, Mountain, Central and eastern) into UTC.
If you live in one of the four US time zones, here are the times when weather balloons are launched each day:
| UNITED STATES |
STANDARD TIME |
DAYLIGHT SAVING TIME |
TIME ZONES |
0Z (00:00 UTC) |
12Z (12:00 UTC) |
0Z (00:00 UTC) |
12Z (12:00 UTC) |
PACIFIC |
4 p.m. |
4 a.m. |
5 p.m. |
5 a.m. |
MOUNTAIN |
5 p.m. | 5 a.m. |
6 p.m. |
6 a.m. |
CENTRAL |
6 p.m. |
6 a.m. |
7 p.m. |
7 a.m. |
EASTERN |
7 p.m. | 7 a.m. | 8 p.m. | 8 a.m. |
Go to this University of Wyoming web site to find the closest weather balloon site to your location. When you see the following map, click on the site closest to your location.
 Click to view enlarged version.
You will next see a table of the most recent weather balloon flight from the location you selected. For example, here is the data from the first kilometer of a balloon flight from Del Rio, Texas. (This flight reached 32 km before the balloon burst and the instruments parachuted down to Earth.) 72261 DRT Del Rio Observations at 12Z 03 Oct 2008
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PRES |
HGHT |
TEMP |
DWPT |
RELH |
MIXR |
DRCT |
SKNT |
THTA |
THTE |
THTV |
hPa |
m |
C |
C |
% |
g/kg |
deg |
knot |
K |
K |
K |
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976.0 |
314 |
18.2 |
13.5 |
74 |
10.06 |
80 |
7 |
293.4 |
322.3 |
295.1 |
964.0 |
421 |
22.0 |
16.0 |
69 |
12 |
120 |
10 |
298.3 |
333.4 |
300.4 |
943.2 |
610 |
22.5 |
14.9 |
62 |
11.45 |
190 |
15 |
300.6 |
334.6 |
302.7 |
925.0 |
780 |
23.0 |
14.0 |
57 |
10.98 |
205 |
22 |
302.8 |
335.6 |
304.8 |
912.0 |
903 |
23.4 |
12.4 |
50 |
10.01 |
205 |
24 |
304.5 |
334.7 |
306.3 |
910.9 |
914 |
23.4 |
12.2 |
50 |
9.92 |
205 |
24 |
304.5 |
334.5 |
306.3 |
884.0 |
1175 |
22.2 |
8.2 |
41 |
7.77 |
192 |
21 |
305.9 |
329.8 |
307.4 |
The data highlighted in blue in the table above is what you can use to make a graph like the one above. The first blue column is the height above the ground in meters. The second blue column is the temperature in degrees Celsius. For an explanation of what weather balloons measure, scroll down to the bottom of any data page for links to descriptions of the data columns.
Save the table you select as a text file (e.g., skytemp.txt). Then upload this file into a computer spreadsheet. You can then make a scatter graph to display the data as it's displayed above.
Finally, mark on the graph the apparent sky temperature you measured with an infrared thermometer to see the altitude at which that temperature was measured during the balloon flight. As discussed above, this does not mean that you measured the temperature at only that altitude. Instead, you measured what might be described as an average temperature up to that altitude and beyond.
Note: The University of Wyoming upper air web site includes an archive of past balloon flights. This is handy if you make some sky temperature measurements on days when you don't have access to a computer.
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Click to view enlarged version.
