What portion of the earth's atmosphere affects the radar from sunrise to sunset?

What portion of the earth's atmosphere affects the radar from sunrise to sunset?

• A. Troposphere
• B. Stratosphere
• C. Exosphere
• D. Ionosphere

Answer: (D)

The ionosphere. This part of the upper atmosphere is ionized by solar radiation, so its electron density rises during daylight. Those free electrons interact with radio waves, causing reflection, refraction, or absorption that can change radar propagation paths. Because sunrise to sunset corresponds to daytime, the ionosphere is the atmospheric layer that most noticeably affects radar during those hours. The lower troposphere is shaped by weather and humidity, not by the sun’s presence in the same way, and the stratosphere and exosphere have only minimal direct impact on typical radar frequencies.

The ionosphere. This part of the upper atmosphere is ionized by solar radiation, so its electron density rises during daylight. Those free electrons interact with radio waves, causing reflection, refraction, or absorption that can change radar propagation paths. Because sunrise to sunset corresponds to daytime, the ionosphere is the atmospheric layer that most noticeably affects radar during those hours. The lower troposphere is shaped by weather and humidity, not by the sun’s presence in the same way, and the stratosphere and exosphere have only minimal direct impact on typical radar frequencies.