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Glossary of Solar Terrestrial Terms
A-B|
C|
D|
E|
F|
G|
H|
I-J|
K|
L|
M|
N|
O|
P-Q|
R|
S|
T|
U|
V|
W|
X-Y|
Z|
Filament
A cool, relatively dense region in the corona that appears dark against the background
chromosphere. On the Sun's limb, filaments are called prominences.
Flare
An explosion on the Sun usually releasing large amounts of energy and particles, and
usually occurring within an active region. Flares are more likely at solar maximum.
fmin
The lowest frequency displayed on an ionogram. It can be an indication of the
amount of absorption occurring in the ionosphere.
foE
The critical frequency of the E region. The maximum frequency which can be refracted
vertically from this region.
foF2
The critical frequency of the F2 region. It is the maximum frequency which can be
refracted vertically by the F2 region. Frequencies higher than this normally penetrate the ionosphere.
F Region
A region in the ionosphere located above about 140 km and capable of refracting HF radio waves.
During the day, the region often divides into a lower F1 region and an upper F2 region. At night
there is only an F region. The F region may be used for HF sky wave communications at any time.
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Educational