Labels:airplane | apron | ball | car | door | escalator | fence | grass | littoral | monitor | person | pole | road | sky | spur gear | tank | tree | umbrella OCR: MA N ETIC SENR M world-wide disturbance the Earth's magnetic tield caused by solar activity. These storms are frequently characteri zed by sudden onset in which the magnetic field undergoes marked changes in the course of an hour or less followed by a gradual return tonormalcy ove several days) SERM cour over ISAPD
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