Weather Maps and Forecasting!

Chantal Marcano, Daisha Wilson, Desire Garrett

What is an isobar and how are isobars constructed on a weather map?

  • Isobars are lines of equal atmospheric (air) pressure drawn on a weather map.
  • In a high-pressure system, the air pressure increases toward the center.
  • In a low-pressure system, it deceases toward the center.
  • Isobars play a major role in determining the speed and direction of wind.
  • Plain, curved lines show areas of equal air pressure
  • When the isobars forms closed (but not always round) circles, the smallest circle in the center indicates a pressure center.
  • This can be either a high pressure system (shown as an “H”) or a low pressure system (shown as an "L".)

How can meteorologists try to predict/ forecast the weather for a given area?

  • · When forecasting daytime temp. , if cloudy skies are expected forecast lower temperatures than you would predict if clear skies were expected
  • · When forecasting nighttime temperatures, if cloudy skies are expected forecast warmer temperatures than you would predict if clear skies were expected
  • · If there is sufficient moisture in the air and a forcing mechanism like a cold front( for example) is approaching the area, then there is an increased probability that precipitation will occur.
There are different methods that can be used to create a forecast the simplest method is called the Persistence Method. It suggests that the conditions at the time of the forecast will not change

If it is cold in Canada and hot in Florida, what kind of weather do you think we will have in Virginia Beach?

It would be cool because the jet stream. The jet stream is a high speed meandering wind current generally moving from a westerly direction at speed often exceeding 250 mph (400kl). The jet stream moves in a wave like motion.

What is an isotherm and how are the isotherms constructed on a weather map?

Isotherms are lines joining places of equal temperature at a given time. Alexander von Humboldt created these lines to elucidate climatic zones and also made drawings that correlated altitude and vegetation. He published a five volume physical geography study that went from 1845-1862. His work was an important part to elaborating on the knowledge of physical science. Even though his paper didn’t last long, it was very specific as well. Isotherms connect different places that have similar to equal temperatures.

What are the symbols for rain, snow, partly cloudy and fog?

Weather maps are created by plotting and tracing weather symbols. The weather maps depend on how much knowledge the meteorologist has on weather and what they believe. The weather is based on computer based models that take many atmospheric factors into account. It includes knowledge of weather maps and teleconnections. Weather includes the clouds in the troposphere and beyond, which includes the sun. The sun has an amazing impact on the weather because the sun develops heat which is beamed on earth.


("Persistence Method:today Equals Tomorrow." Persistence Method:today Equals Tomorrow. N.p., n.d. Web. 10 Jan. 2013.)

"Isobar." Encyclopedia Americana. Grolier Online, 2013. Web. 10 Jan. 2013.

Burroughs, W. J. (1996). Forecasting Today. Weather (p. 88). Alexandria, Va.: Time Life Books.

"How to Read a Weather Map, with Examples - wikiHow." WikiHow. N.p., n.d. Web. 14 Jan. 2013. <>.

Geography. (2013). Encyclopedia Americana. Retrieved January 10, 2013, from Grolier Online