Which Device Records the Duration of Sunshine in a Day?
To record the duration of sunshine in a day (i.e., the number of hours/minutes when the sun is shining), the standard instrument is the Sunshine recorder, commonly the Campbell–Stokes sunshine recorder. The recorder inscribes a burn trace on specially designed cards that corresponds to the actual bright sunshine duration. 2
A quick elimination of the other options:
- Thermometer measures temperature (often air temperature), not how long the sun shines.
- Pyranometer measures solar radiation intensity, not sunshine duration (hours of bright sunshine).
- Pyroheliometer measures direct solar radiation, not sunshine duration.
A useful conceptual distinction is shown below:
Correct choice (MCQ): (iv) Sunshine recorder.
Footnotes
-
World Meteorological Organization (WMO) — Sunshine duration / sunshine recorder information - WMO documentation explains sunshine duration measurement practices (context: sunshine recorders and sunshine hours). ↩
-
Campbell–Stokes sunshine recorder (Wikipedia) - Describes how the sunshine recorder records sunshine duration. ↩
-
Thermometer (Wikipedia) - Defines thermometers as instruments for measuring temperature. ↩
-
Pyranometer (Wikipedia) - Defines pyranometers as instruments that measure global solar irradiance. ↩
-
Pyroheliometer (Wikipedia) - Defines pyroheliometers as instruments for measuring direct (beam) solar irradiance. ↩
type="tip" title="Pro Tip" In MCQs, look for wording like “duration of sunshine,” “sunshine hours,” or “bright sunshine”—those strongly indicate a sunshine recorder, not radiation meters or thermometers. 2
Footnotes
-
World Meteorological Organization (WMO) — Sunshine duration / sunshine recorder information - WMO documentation explains sunshine duration measurement practices (context: sunshine recorders and sunshine hours). ↩
-
Campbell–Stokes sunshine recorder (Wikipedia) - Describes how the sunshine recorder records sunshine duration. ↩
type="warning" title="Common Confusion" Pyranometers and pyroheliometers measure how strong the sunlight is (irradiance), not how long it is sufficiently bright to count as “sunshine hours.” 2
Footnotes
-
Pyranometer (Wikipedia) - Defines pyranometers as instruments that measure global solar irradiance. ↩
-
Pyroheliometer (Wikipedia) - Defines pyroheliometers as instruments for measuring direct (beam) solar irradiance. ↩
Mapping the Options to What They Measure
Counts bright sunshine time
Sunshine durationRecorded using a sunshine recorder (e.g., Campbell–Stokes). 2"
Footnotes
-
World Meteorological Organization (WMO) — Sunshine duration / sunshine recorder information - WMO documentation explains sunshine duration measurement practices (context: sunshine recorders and sunshine hours). ↩
-
Campbell–Stokes sunshine recorder (Wikipedia) - Describes how the sunshine recorder records sunshine duration. ↩
Measures sunlight intensity
Solar irradiancePyranometers measure global irradiance; pyroheliometers measure direct beam irradiance. 2"
Footnotes
-
Pyranometer (Wikipedia) - Defines pyranometers as instruments that measure global solar irradiance. ↩
-
Pyroheliometer (Wikipedia) - Defines pyroheliometers as instruments for measuring direct (beam) solar irradiance. ↩
Measures thermal state
TemperatureThermometers measure temperature, not sunshine duration. "
Footnotes
-
Thermometer (Wikipedia) - Defines thermometers as instruments for measuring temperature. ↩
What Each Instrument Primarily Measures
High-level comparison for answering the question.
Quick FAQ for This MCQ
Knowledge Check
Which device is used to record the duration of sunshine in a day?