Customize - Urban Dictionary Store

Pro Customization

Create unique products with your own words and definitions

Preview

Personalize Your Design

Your Word

Your Definition

That portion of the ionosphere existing between [approximately] 160 and 400 km above the surface of the [Earth], consisting of layers of increased free-electron density caused by the ionizing effect of solar radiation.  Note 1:  The F region reflects normal-incident frequencies at or below the critical frequency ([approximately] 10 MHz) and partially absorbs waves of higher frequency.  Note 2:  The F1 layer exists from about 160 to 250 km above the surface of the Earth and only during daylight hours.  Though fairly regular in its [characteristics], it is not observable everywhere or on all days. The principal reflecting layer during the summer for paths of 2,000 to 3,500 km is the F1 layer.  The F1 layer has approximately 5 ´ 105 e/cm3 (free electrons per cubic centimeter) at noontime and minimum sunspot activity, and increases to roughly 2 ´ 106 e/cm3 during maximum sunspot activity.  The density falls off to below 104 e/cm3 at night.  Note 3: The F1 layer merges into the F2 layer at night.  Note 4:  The F2 layer exists from about 250 to 400 km above the surface of the Earth.  The F2 layer is the principal reflecting layer for HF [communications] during both day and night. The horizon-limited distance for one-hop F2 propagation is usually around 4,000 km.  The F2 layer has about 106 e/cm3.  However, variations are usually large, irregular, and particularly pronounced during magnetic storms.

Text may be too long

Menu

Pro Customization

Preview

Personalize Your Design

Shopping Assistant