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Learning how meteorologists use technology to track storms and predict the future weather.
Imagine you are in charge of a billion-dollar rocket launch. How do you decide if the sky is safe enough to fly, or if a hidden storm is about to strike?
To predict the future, meteorologists first need to measure the present. They use specific tools to track the 'ingredients' of weather. An anemometer measures wind speed by catching the wind in small cups, usually measured in . A barometer measures atmospheric pressure, which is the weight of the air pressing down on Earth. This is often measured in millibars () or hectopascals (). Finally, a hygrometer measures humidity, or the amount of water vapor in the air, expressed as a percentage. When these three measurements change, it signals that the weather is about to shift.
Suppose you want to know if the air is 'heavy' and likely to bring clear skies or if it is 'light' and likely to bring rain. 1. You check the Barometer. 2. You see a reading of . 3. Since high pressure usually means fair weather, you predict a sunny day.
Quick Check
Which tool would you use if you wanted to see how fast a hurricane's winds are moving?
Answer
An anemometer.
Weather maps use symbols to show how air masses move. Isobars are lines that connect areas with the same atmospheric pressure. If isobars are close together, the pressure changes quickly over a short distance, creating high wind speeds. Fronts represent the boundaries between warm and cold air. A Cold Front is shown as a blue line with triangles; it often brings sudden thunderstorms and cooler temperatures. A Warm Front is a red line with semicircles, usually bringing steady, light rain followed by warmer, clearer weather.
Look at two points on a map, Point A and Point B. 1. At Point A, the isobars are apart. 2. At Point B, the isobars are apart. 3. Because the pressure gradient is steeper where lines are closer, Point B will have much higher wind speeds than Point A.
Quick Check
If you see a blue line with triangles on a map moving toward your city, what change should you expect in the temperature?
Answer
The temperature will likely drop (get colder).
Predicting the weather involves looking at trends. If the barometric pressure is falling (), it usually means a low-pressure system is arriving, which brings clouds and precipitation. If the pressure is rising (), the weather will likely clear up. By tracking the speed of a front—for example, a cold front moving at —you can estimate exactly when a storm will hit a city away using the formula .
A meteorologist observes a cold front west of 'City X'. The front is moving east at . 1. Calculate the arrival time: hours. 2. If it is currently 10:00 AM, the storm will arrive at 6:00 PM. 3. Forecast: Expect a sudden drop in temperature and possible thunderstorms by early evening, followed by clear, cool skies tomorrow.
If a barometer reading changes from to , what weather change is most likely?
On a weather map, what does a red line with semicircles represent?
When isobars are spaced very far apart on a map, it indicates that the area is experiencing very strong, gusty winds.
Review Tomorrow
In 24 hours, try to list the three main weather tools and explain which one you would use to predict a coming storm.
Practice Activity
Find a weather map in a newspaper or online. Identify one isobar and one front, then try to guess if the pressure in your area will rise or fall over the next day.