How a Tipping Bucket Counts Rain

Written by Studio AM.

An automated rain gauge can measure a shower without holding all the water that falls into it. At the top, a funnel directs rain toward a tiny seesaw with two cups. One cup is positioned beneath the funnel. When the collected water reaches a set amount, its weight tips the seesaw, empties that cup, and moves the second cup into position to collect rain.

Each tip passes a magnet by a switch, creating an electrical pulse. A logger records the pulse and its time. Because the funnel's catch area and the cup's capacity are known, software converts the number of tips into rainfall depth. Closely spaced pulses indicate heavier rain; a longer gap can mean lighter rain or a pause. The water itself simply drains away.

This tidy mechanism still needs field care. A screen helps keep large debris out, but fine material can still collect. Leaves or insects can block the funnel, wind can make some drops miss it, and a gauge that is not level will tip unevenly. Snow also needs special equipment because it may not flow through the funnel as liquid. For that reason, technicians inspect the opening, level the base, and compare readings with nearby instruments. The gauge automates counting, but reliable data still depends on careful placement and maintenance.

Questions

Choose an answer. The explanation appears after you answer.

  1. Question 1 of 4

    Which statement best summarizes the passage?

  2. Question 2 of 4

    Why could an unlevel gauge produce an unreliable total?

  3. Question 3 of 4

    What is an electrical "pulse" in this passage?

  4. Question 4 of 4

    What do closely spaced pulses indicate?

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