^^Campo magnetico terrestre. NOAA.

Campo magnetico dove siamo noi, Massa 44°N 11°E

47.000 nT Main Field Total Intensity
60° Main Field Inclination
2° Main Field Declination

Intensity.
Isodynamic chart

   

Inclination
Isoclinic chart

   

Declination
Isogonic chart

Intensity 

The intensity of the field is greatest near the poles and weaker near the Equator. It is generally reported in nanoteslas (nT) or gauss, with 1 gauss = 100,000 nT. It ranges from about 25,000–65,000 nT, or 0.25–0.65 gauss. By comparison, a strong refrigerator magnet has a field of about 100 gauss.
A map of intensity contours is called an isodynamic chart. A minimum intensity occurs over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.

Inclination

The inclination is given by an angle that can assume values between -90° (up) to 90° (down). In the northern hemisphere, the field points down. It is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal (0°) at the magnetic equator. It continues to rotate upwards until it is straight up at the South Magnetic Pole. Inclination can be measured with a dip circle.
An isoclinic chart (map of inclination contours) for the Earth's magnetic field is shown on the right.

Declination. Isogonic chart (map of declination contours)

Isogonic lines give the declination in signed degrees. Declination is positive for an eastward deviation of the field relative to true north. It can be estimated by comparing the magnetic north/south heading on a compass with the direction of a celestial pole. Maps typically include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination). 

Links

  1. www.ngdc.noaa.gov/geomag/WMM/ The World Magnetic Model
    1. NOAA National Geophysical Data Center. Geomagnetic Data & Information
    2. NOAA National Oceanic and Atmosferic Administration
  2. www.ngdc.noaa.gov/geomag Geomagnetismo

 

 

Guida ins

Alter espo

Intensity.

Isodynamic chart

 Inclination

Isoclinic chart

 Declination

Isogonic chart

 

Intensity

   The intensity of the field is greatest near the poles and weaker near the Equator. It is generally reported in nanoteslas (nT) or gauss, with 1 gauss = 100,000 nT. It ranges from about 25,000–65,000 nT, or 0.25–0.65 gauss. By comparison, a strong refrigerator magnet has a field of about 100 gauss.
A map of intensity contours is called an isodynamic chart. A minimum intensity occurs over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.

Inclination
 

The inclination is given by an angle that can assume values between -90° (up) to 90° (down). In the northern hemisphere, the field points down. It is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal (0°) at the magnetic equator. It continues to rotate upwards until it is straight up at the South Magnetic Pole. Inclination can be measured with a dip circle.
An isoclinic chart (map of inclination contours) for the Earth's magnetic field is shown on the right.

Declination. Isogonic chart (map of declination contours)
  Isogonic lines give the declination in signed degrees. Declination is positive for an eastward deviation of the field relative to true north. It can be estimated by comparing the magnetic north/south heading on a compass with the direction of a celestial pole. Maps typically include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination).