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Weather map

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A weather map provides a view of weather elements over a specified geographical area at a specified time and was invented by Sir Francis Galton. It is obtained by plotting or tracing the values of relevant quantities such as pressure, temperature, cloud cover, and others, onto a geographical map.

Look at the weather map on the left.
It shows the weather for Thursday (15/6/00).
Predict which day of the following weekend would be the best day to have a picnic in Melbourne, Saturday(17/6/00) or Sunday(18/6/00)?

Weather Maps
One of the tools that forecasters use to identify and locate air masses, pressure systems, and fronts is the weather map. These maps are normally prepared at 3- or 6-hour intervals.

Weather maps that are produced for the portion of the atmosphere above the lower troposphere, generally at and above 850 mb. Isolines on these maps usually represent the heights of a constant pressure surface, such as the 500 mb surface.
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Use a weather map to look up the temperatures of cities around the world and discover how hot each gets in the summer and how cold each gets in the winter. Compare these figures with your town. Ask your children if they can think of reasons why different locations have different temperatures.

National ~s
National Radar
National Satellite
National Precipitation
National Temperatures
National Wind Speed ...

Line on a ~ joining points of equal pressure.
Lines drawn through positions with the same temperatures.

A line on a ~ linking areas with equal air pressure
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Weather services like WeatherOnline or the Met Office are using the data for plotting ~s, such as the mean-sea-level pressure chart, which is also known simply as surface chart.

A line drawn on a ~ connecting points of equal pressure is called an "isobar". Isobars are generated from mean sea-level pressure reports and are given in millibars.

Isobar- A line on a ~ that surrounds an area with the same atmospheric pressure.
Isotherm- A line on a ~ that surrounds an area with the same temperature.
Jet Stream- A narrow band of winds blowing high in the troposphere at speeds in excess of 57 miles per hour or greater.

The line drawn on a ~ connecting points of equal barometric pressure.
The line drawn on a ~ connecting points of equal dew point.

with some major flare events beginning 10 to 20 minutes after the flare maximum, and can last for hoursRadio EventFlares with Centimetric Bursts and/or definite Ionospheric Event (SID)RadiofacsimileAlso known as HF FAX, radiofax or weatherfax, is a means of broadcasting graphic ~s ...

Station ModelA specified pattern for plotting, on a ~, the meteorological symbols that represent the state of the weather at a particular observing station.Station PressureThe absolute air pressure at a given reporting station.

Cold PoolA region of relatively cold air, represented on a ~ analysis as a relative minimum in temperature surrounded by closed isotherms. Cold pools aloft represent regions of relatively low stability, while surface-based cold pools are regions of relatively stable air.

Isobaric ChartA ~ representing conditions on a surface of equal atmospheric pressure. For example, a 500 mb chart will display conditions at the level of the atmosphere at which the atmospheric pressure is 500 mb.

A continental cold air mass is a high pressure center, and it is represented on the ~ by the capital letter "H". It will change as it moves southward, and will become a "transformed continental air mass" when it reaches east China.

The isobars on a ~ are usually drawn with a 4 mb contour interval, so to get the pressure gradient we multiply the above figure by 4 divided by the distance between the isobars in degrees of latitude. Of course, we can easily adjust this if we use km or miles instead.

upper-air weather chartWeather maps that are produced for the portion of the atmosphere above the lower troposphere, generally at and above 850 millibars. Isolines on these maps usually represent the heights of a constant pressure surface, such as the 500 millibars surface.

Constant Pressure Maps: A ~ of a particular constant pressure surface, such as the 50 kPa or 500 mb surface, in which atmospheric pressure is uniform everywhere.

Isopleth A line on a ~ connecting constant thickness (layer of atmosphere).
Isotach A line on a ~ connecting points of equal wind speed.
Isotherm A line on a ~ connecting points of equal temperature.

Isotherm - A line of equal temperature on a ~.
Jet Stream - Strong winds concentrated within a narrow band in the upper atmosphere. It normally refers to horizontal, high -altitude winds. The jet stream often "steers" surface features such as front and low pressure systems.

Synoptic scale The typical ~ scale that shows features such as high- and low-pressure areas and fronts over a distance spanning a continent.
Sensible heat Heat that can be measured with a thermometer; a measure of the concentration of kinetic energy from molecular motion.

ISOBAR: A line of equal barometric pressure on a ~.
ITCZ: Inter-tropical Convergence Zone. The region where the northeasterly and southeasterly tradewinds converge, forming an often continuous band of clouds or thunderstorms near the equator.

Isobar - A line on a ~ that connects points of equal pressure. On a ~, isobars extend around areas of high and low pressure.

Isobars Lines drawn on a ~ joining places of equal barometric pressure.
Isothermal Of or indicating equality of temperature.
Isotherms Lines connecting points of equal temperature on a ~.

Isobar- the line of equal pressure denoted on surface ~s.
Isotherm- the line of equal temperature denoted on surface ~s.
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Air pressure tendency Change in air pressure with time; on a surface ~, the air pressure change over the prior 3 hours.
Albedo The fraction or percent of radiation striking a surface that is reflected by that surface.

Most high and low pressure areas seen on ~s are synoptic-scale systems.
NOAA National Weather Service - Cite This Source - This Definition
Browse Related Terms: ADJ, depression, Doldrums, Filling, LOPRES, Mesolow, Pressure Couplet, Sub-synoptic Low, SYNOP, Synoptic-scale, Warm Core Low ...

Low: A region of low pressure, marked as "L" on a ~. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds. See Cyclone.

15. isobar
A line of equal barometric pressure on a ~.
16. Isodrosotherm
A line connecting points of equal dew point temperature.

synoptic chart—A chart, such as the familiar ~, which depicts the distribution of meteorological conditions over an area at a given time.
target—In radar, any of the many types of objects detected by radar.

The saddle point (sometimes called a "col") refers to a point in the air pressure pattern depicted on a ~. A saddle point is both the lowest point of pressure in a trough or depression between two ridges (high pressure systems) and the highest point in a ridge between two lows.

The temperature so read is usually called 'the air temperature' and it is these values that appear, for example, in the World Cities reports in newspapers/teletext, or plotted on standard synoptic charts, and also it is at this level that the forecast temperatures seen on tv ~s are based.

Fronts: In temperate climates air mass discontinuities are demarcated by Fronts . These are not featured on the Malawi ~.
Surface convergence: An upwelling of excess air as air streams from different directions converge.

Geostrophic wind - a theoretical wind which blows along the isobars on a ~. Pretty good of actual winds high above the ground.

col - (Also called saddle point, neutral point.) In meteorology, the point of intersection of a trough and a ridge in the pressure pattern of a ~. It is the point of relatively lowest pressure between two highs and the point of relatively highest pressure between two lows.

ISOBAR - A line connecting equal points of barometric pressure, which are usually depicted on ~s and charts by meteorologists.
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INVERTED TROUGH - A trough of low pressure appearing as an "upside down" trough on a ~. These are troughs where the flow they are embedded in is from an Easterly direction in the Northern hemisphere.

(or large scale) A size scale referring generally to weather systems with horizontal dimensions of several hundred kilometres or more. Most high and low pressure areas seen on ~s are synoptic-scale systems. Compare with mesoscale, storm-scale.
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WaveIn meteorology any pattern identifiable on a ~ that has a cyclic pattern or a small cyclonic circulation in the early stages of development that moves along a cold front. In Canada, A wave, in meteorology, is the intersection of warm and cold fronts.

See also: See also: What is the meaning of Weather, Pressure, Air, Temperature, Surface?

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