— Tidemarker

Tidemarker is a browser-based guide to observing and interpreting local weather using a home barometer, cloud formations, and a consistent observation log. Its pressure-trend interpreter compares readings taken three hours apart, classifies the change using conventional tendency bands, and explains how wind direction and hemisphere can help locate low pressure. The tool runs entirely in the browser and clamps inputs to a stated pressure range.

The site’s field guides explain how to set and read an aneroid barometer, including altitude correction, calibration against a nearby official station, and signs that an instrument may need servicing. A cloud-identification guide introduces the ten genera in the WMO classification, their typical heights and appearances, and sequences that can signal changing weather. Tidemarker also provides practical instructions for keeping comparable observations, covering recording times, pressure, temperature, wind, cloud cover, precipitation, and suitable instrument placement. Together, its interactive interpreter and reference material help home observers build a weather picture from measurements and what they see outdoors, rather than relying on barometer labels or isolated readings.