Question
What is a geomagnetic storm?
Answer Options
- A) A sudden drop in the solar flux index
- B) A thunderstorm that affects radio propagation
- C) Ripples in the geomagnetic force
- D) A temporary disturbance in Earth’s geomagnetic field
Correct Answer: D
Explanation
A geomagnetic storm is a temporary and often severe disturbance of the Earth’s magnetosphere caused by a solar event, such as a Coronal Mass Ejection (CME) or a high-speed stream of solar wind from a coronal hole. These events inject massive amounts of charged particles and energy into the magnetosphere.
These disturbances are monitored by indices like the K-index and the A-index, which measure the stability of the geomagnetic field. A geomagnetic storm significantly impacts HF radio communication, especially at high latitudes, typically leading to a decrease in the Maximum Usable Frequency (MUF) and an increase in signal absorption.
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