Weather Radar Explained — How It Works

How Weather Radar Works

A weather radar station sends out pulses of microwave energy. When those pulses hit raindrops, snowflakes, or hail, some energy bounces back. The radar measures the returned signal to determine what precipitation is out there.

What the Colours Mean

Radar maps use colour scales to show precipitation intensity:

Types of Weather Radar

• Reflectivity — Shows where precipitation is and how heavy it is (the standard coloured map)
• Doppler velocity — Shows whether precipitation is moving toward or away from the radar, crucial for detecting rotation in storms (tornados)
• Dual-polarisation — Sends both horizontal and vertical pulses to distinguish rain from hail, snow, and debris

Reading a Radar Loop

Radar animations show you:

• Which direction storms are moving
• How fast they are travelling
• Whether storms are growing or weakening
• When rain will reach your location

Radar Limitations

• Radar beams travel in straight lines, so the curve of the Earth creates blind spots far from stations
• Mountains can block radar signals
• Very light drizzle or high-altitude virga (rain that evaporates before reaching ground) may not show clearly

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