Summary
Weather data is collected using various instruments to measure conditions like temperature, rainfall, air pressure, wind speed, and humidity. Accurate data collection is crucial for weather forecasting, climate studies, and hazard management.
- Thermometer — measures temperature, usually housed in a Stevenson screen. Example: Used to record daily maximum and minimum temperatures.
- Rain Gauge — collects precipitation in a funnel leading to a measuring cylinder. Example: Measures rainfall in millimeters.
- Barometer — measures air pressure in millibars or hectopascals. Example: Indicates high or low pressure systems.
- Anemometer — measures wind speed using rotating cups. Example: Records speed in knots or kilometers per hour.
- Wind Vane — shows wind direction by pointing into the wind. Example: A north wind vane indicates wind coming from the north.
- Hygrometer — measures humidity using wet and dry bulb thermometers. Example: Calculates relative humidity as a percentage.
- Sunshine Recorder — measures sunshine duration with a glass sphere focusing sunlight onto a card. Example: Records hours of bright sunshine per day.
Exam Tips
Key Definitions to Remember
- Weather: Day-to-day atmospheric conditions
- Climate: Average weather over 30+ years
- Stevenson Screen: White box housing thermometers
- Rain Gauge: Collects precipitation in mm
- Barometer: Measures air pressure in mb/hPa
- Anemometer: Measures wind speed
- Wind Vane: Shows wind direction (from)
- Hygrometer: Measures humidity
Common Confusions
- Confusing weather with climate
- Misunderstanding wind direction (it's where the wind comes from)
Typical Exam Questions
- What is the purpose of a Stevenson screen? To house thermometers and protect them from direct sunlight and rain.
- How does a rain gauge work? It collects rain in a funnel and measures it in a cylinder.
- Why is instrument siting important? To ensure accurate and representative data collection.
What Examiners Usually Test
- Descriptions of weather instruments and their functions
- Correct siting of instruments
- Interpretation of weather data from tables and graphs
- Understanding of manual vs. automatic weather stations