Tropical Storms--Measuring and recording weather conditions

Tropical storms are a moving hazard, so they must be tracked and forecasts made of their future progress. That is what meteorologists do. 

If they can measure how they are developing, they they can warn people in the predicted path of the storm. This should give people time to prepare such as moving to higher ground (avoid storm surge) or to an emergency shelter. Homes can be made ready by boarding up windows and moving furniture upstairs. 

The media which includes TV, radio and the Internet play an important role in keeping the general public updated about the storm and where it is expected to go. 

How do meteorologists track and predict the movement of tropical storms? The data they work on comes from a number of different sources.

Weather Stations

There is a global network of weather stations that track the movement of tropical storms. Some are manned, some are automatic, some monitor the weather all the time and others just at set hours during the day and night.

Once all this information about pressure, temperature, humidity, winds and so on is collected and put together, it can be used to predict what will happen to the storm. Will it deepen, with an increase in rainfall and wind speeds or will the storm begin to weaken and fizzle out?

Weather Satellites

These are important for viewing large weather systems on a worldwide scale. They show cloud formation, large weather events such as hurricanes, and other global weather systems. With satellites, forecasters can see weather systems such as tropical storms.

On each satellite, there are 2 types of sensor. One is a visible light sensor called the imager. It works like a camera in space and helps gather information on cloud movements and patterns. This sensory can only be used during daylight hours, since it works by capturing reflected light to create images.

The second sensory is the sounder. It is an infrared sensor that reads temperatures. The higher the temperature of the object, the more energy it emits. This sensory allows satellites to measure the amount of energy radiated by the Earth's surface, clouds, oceans, air etc. Infrared sensors can be used at night which is helpful for forecasters, considering that the imagers can only pick up data during daylight hours.

Radar

Doppler radar is another important meteorological tool. Radar works a little differently from satellite sensors. Instead of reading reflected light or energy, radar measures reflected sound waves. When sound waves are broadcast from a radar mast and come into contact with a moving object, such as a rain cloud, radar will give information about the direction and speed of the object's movement. By using radar and getting a 'picture' of precipitation (e.g water falling to the ground) on the radar screen, meteorologists are able to track a storm's progress over time. 

Fieldwork Opportunities: Hazardous Environments

Fieldwork Opportunities: Hazardous Environments

Measuring, collecting and recording weather data:

• During the passage of a tropical storm, local weather stations will record an enormous increase in wind speed and rainfall.
• Instrument area is used to measure local weather conditions in calmer, drier conditions-providing primary data.
• Care and accuracy important when measuring weather-instrument itself has to be suitable as well as its use accurate.
• Should have an easy to complete record sheet showing date, time and columns for each element of the weather you have instruments for. Eg maximum/minimum temperature and rainfall.
• Records should be kept daily and for at least a week. Readings should be taken preferably at same time each day.

Rain Gauge:

• It should be placed in open space so it can collect rain water straight from the sky.
• Rain is collected in a measuring flask and the measurement can be read easily.
• Once reading is noted, the water has to be tipped away daily.

Stevenson Screen:

• Instruments used to measure temperature and humidity should be kept inside a Stevenson Screen.
• It’s a wooden box used to shade from direct sunlight and radiation so that the instruments inside can measure air temperature.
• It’s painted white to reflect sunlight and has vents to allow free flow of air. This makes the readings fair.
• Maximum-minimum thermometer housed inside measures the highest and lowest temperature, often within a 24-hour period. –weather data should be standardised.
• Readings have to be taken so that they can be compared with those taken at other places and at other times.
• After noting temperature readings, the thermometer has to be reset by sliding the magnetic base over the mercury columns.

Cup Anemometer and wind valve:

• Wind valve measures wind direction.
• Cup anemometer is a weather instrument that measures wind speed/strength.
• There are 3 to 4 cups mounted on a vertical pole. The cups catch the blowing wind and turn the pole.
• Each time the anemometer makes a full rotation, the wind speed is measured by the number of revolutions per minute (RPM).
• The number of revolutions is recorded over time and an average is determined.