STEM与日常科技·英语30篇（2）

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气象雷达如何探测降雨强度与移动

Weather radar sends out microwave pulses that bounce off raindrops in the sky.
By measuring how much energy returns and how long it takes, computers calculate distance and intensity.
Larger or more numerous drops reflect stronger signals, showing heavy versus light rain.
Doppler radar also detects motion, so it can track storm movement and rotation speed.
Meteorologists combine data from many radars to build real-time national precipitation maps.
This helps issue flash flood warnings hours before heavy rain reaches cities.
Radar cannot see inside mountains, so gaps exist in terrain-heavy regions.
New dual-polarization radars send both horizontal and vertical pulses for better drop shape analysis.
They distinguish rain from hail, snow, or even birds flying near airports.
Though powerful, radar still needs ground sensors to confirm rainfall amounts accurately.