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What is the name given to the line on a weather chart that connects all points having the same atmospheric pressure?

  • A

    Isobar

  • B

    Isogonal

  • C

    Isotherm

  • D

    Isotach

Refer to figure.
Iso means equal. Bar is an amount of pressure (1 bar is roughly 1013.25 hPa). So, combining this you get the definition Equal amount of pressure.

KEY RULE:
 
ISOBAR = equal PRESSURE
ISOTHERM = equal TEMPERATURE
ISOTACH = equal WIND SPEED
ISOGONAL (or ISOGON) = equal MAGNETIC VARIATION. 

Isobars are the fundamental lines on synoptic weather charts, spaced at 2, 4, or 8 hPa intervals.

Note: The isobars are generated from pressure reports at ground level, which are then corrected down to the expected pressure at sea level using the actual temperature. This means that the isobars on a surface pressure chart are lines of constant QFF, which is the expected sea level pressure (when sea level pressure cannot be directly measured).

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