Learning Lesson: The Daily Ups and Downs

Probably the most often asked question in weather is "What is the temperature?" The depends upon many variables but most frequenly it is the time of day that has the most influence on the change of temperature. One often hears only the high and low temperature for the day without realizing how the temperature changes hourly during the day.

1. Go to the following National Weather Service website: www.srh.weather.gov.
   
   
2. Enter your zip code in the search box located on the upper left side of that website. Press "Go."
   
   
3. Under "Current Conditions" should be the nearest observation site to the zip code entered. Click "2 Day History" or, for a list of additional sites in your area, click "More Local WX" then select the name of a observation site.
   
   
4. You will see a page the looks like this...
   
   This information is that location's weather observations for the previous 48 hours. The most recent observation is listed first. Weather observations are recorded a few minutes prior to the top of each hour. For example, if the observation time is 0953 then the observation time is called the 10:00 a.m. observation. If the observation time is 1953, then the observation is 2000 (using the 24-hour clock) or 8:00 p.m.
   
   
5. Have the students label the time axis of their graph beginning with the last (bottom) observations. They can round the time to the nearest whole hour. Label in red or otherwise indicate midnight and noon.
   
   
6. Have the students label the temperature axis. (Look at the 6-hour minimum temperature column and round down, to the nearest 0 or 5, the lowest value observed. For example, if the lowest temperature in the minimum column is 64 then begin labeling the temperature axis at 60.
   
   
7. With the axis labeled, have the student place a dot for each hourly air temperature on the graph.
   
   
8. Now connect the dots.

On an average day, without any storms or fronts nearby, the temperature does not increase or decrease in straight lines. A normal temperature graph will have a basic saw tooth appearence. The actual temperature trace the students will create can vary greatly depending upon the weather. You may not see the saw tooth pattern if a cold front has passed your location recently.

Also, the maximum and minimum temperatures do not occur at noon and midnight. Discuss why. (Sunlight strikes the Earth's surface and the surface heats up. The air in contact with the surface heats up. At night, with no sunlight, the Earth continues to emit infrared radiation, as does much of the atmosphere and the Earth's surface cools. Because of the air, this does not happen instantaneously but is seen as the lag.)

Also, why is there a lag in heating and cooling over the year? Recall, maximum solar radiation in the Northern Hemisphere occurs in June but warmest weather is usually not until late July and early August. In winter, the least amount of solar radiation is in late December but it is usually late January and early February during which we experience the coldest weather.

Begin each day with the check of the weather forecast for your area to minimize your risk to extreme weather regardless if it is heat waves, tornadoes, flooding rains or any other type of hazardous conditions.

Entering your zip code in the search box located at www.srh.weather.gov will provide you with the forecast direct from the professionals of your nearby NWS Forecast Office. We are here 24 hours a day, 365 days a year. No one knows your weather better than we do.

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