English Weather Station: Instrument Physics and the Stevenson Screen

What Instruments Measure

A weather station typically includes several key instruments: a wet bulb thermometer, a dry bulb thermometer, a cup anemometer with vane, a rain gauge, and a barometer. Each instrument measures different aspects of the atmosphere to provide comprehensive data on temperature, wind speed, precipitation, and air pressure.

The Stevenson screen is a protective enclosure that houses these instruments, shielding them from direct sunlight, wind, and other environmental factors to ensure accurate readings.

Why the Stevenson Screen Matters

The Stevenson screen is crucial for maintaining consistent and reliable measurements. It protects thermometers from solar radiation, which can significantly alter temperature readings. The screen also shields instruments from wind gusts that could affect anemometer readings or cause rain gauge errors.

By ensuring these instruments are not exposed to extreme conditions, the Stevenson screen allows meteorologists to accurately interpret data and make informed weather predictions.

How Instruments Function

The wet bulb thermometer measures relative humidity by cooling down as water evaporates from a cloth wrapped around it. The dry bulb thermometer simply measures the ambient air temperature without any moisture influence.

The cup anemometer with vane measures wind speed and direction, while the rain gauge collects precipitation over time to determine rainfall amounts. The barometer measures atmospheric pressure, which can indicate changes in weather patterns.

Why Each Instrument Reads Differently

Despite being part of the same weather station, each instrument reads differently because they are designed to measure distinct properties and are affected by various environmental factors. For instance, a wet bulb thermometer will show lower temperatures than a dry bulb due to evaporation cooling.

These differences highlight the importance of using multiple instruments in conjunction with one another for comprehensive weather analysis.

Frequently asked questions

Try it live

Everything above runs in your browser — open English Weather Station: Instrument Physics and the Stevenson Screen and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.