Definition

1. Noun:
   • A region of the ionosphere: The E region is a specific layer of the Earth's ionosphere, located at an altitude of approximately 50 to 90 miles (about 80 to 145 kilometers) above the Earth's surface.
   • A layer that reflects radio waves: This atmospheric layer is characterized by its ability to reflect medium-frequency (medium-length) radio waves, which is crucial for certain types of long-distance radio communication.

Usage Examples

• Noun:
  • The E region is most pronounced during daylight hours.
  • Radio signals can bounce off the E region to travel beyond the horizon.
  • Scientists study the E region to understand its impact on communication systems.

Advanced Usage

• "The E region's density": Refers to the concentration of ionized particles within this specific ionospheric layer.
  • Solar activity greatly affects the E region's density.
• "To reflect off the E region": Describes the action of radio waves bouncing back from this layer.
  • The amateur radio operator hoped his signal would reflect off the E region.

Variants and Related Words

• E layer (noun): A synonym for the E region, used interchangeably in atmospheric and radio science.
  • The E layer disappears at night.
• Ionosphere (noun): The broader region of the Earth's upper atmosphere that contains the E region and other layers (D, F1, F2).
• Sporadic E (noun): A specific, irregular phenomenon within the E region where small, dense clouds of ionization form, allowing for unusual long-distance radio propagation.
  • During the summer, sporadic E can enable VHF radio contacts over thousands of miles.

Synonyms

• E layer: The most direct synonym.
• Kennelly-Heaviside layer: A historical name for the ionospheric layer, though this term sometimes refers more specifically to the E region.

Related Phrases

• "E region propagation": The method of long-distance radio communication achieved by signals reflecting from the E region.
  • He specializes in studying E region propagation.
• "E region critical frequency": The highest frequency at which a radio wave can be reflected vertically from the E region.
  • Measuring the E region critical frequency is essential for predicting radio conditions.

Noun

1. a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length