Weather measurements have existed in one form or another for as long as humans have recorded history. Recording and attempting to predict or decipher the mystery of weather patterns allows humans to plan for the future, grow crops, stay warm, and ensure they don't get flooded out.
Modern global weather records began in 1880. Although methodical records were started in the 1850s, the data was not globally collected and compared until 1880. So when it is stated that "this year is the hottest since records began," it means that it is the hottest year since 1880.
Over the centuries, much of the equipment we use to measure the weather has advanced into high-tech instruments. But, there is also some weather measuring devices that have stayed pretty much the same.
So join us as we explore the purpose, use, and history of seven types of weather measurement.
Meteorological offices, or weather stations, generally have thermometers, barometers, hygrometers, anemometers, rain gauges, windsocks, weather vanes, and pyranometers. They may also have other more specified equipment that is needed to measure local climatic variations.
Weather stations are located on both land and sea. They use specialist equipment to take atmospheric readings, record the weather, and then use their findings to provide forecasts and observe climatic patterns and changes over a longer period of time.
So let's now jump in and look at the first on our list of weather-measuring devices, perhaps the most famous of them all: the thermometer.
Thermometers
The thermometer is, in many ways, the flagship weather measurement system. Thermometers measure the temperature of things and, when it comes to weather, are used for measuring air and sea surface temperature.
The use of thermometers and proto-thermometers dates back thousands of years, and the honing of the instrument we call the thermometer has been a gradual development rather than a singular invention.
Many historians credit Hero of Alexandria with creating the first version of an early thermometer. He lived between 10-70AD and recognised that air expanded and contracted when the temperature changed. He wrote about his invention, which consisted of a closed tube filled with air and water. The expansion and contraction of the air caused the water to move along the tube, which in some ways is very similar to a modern thermometer.
In the 18th century, the inventor Daniel Gabriel Fahrenheit (who gave his name to a whole temperature measurement unit) created the first mercury-based, precise thermometer that forms the basis of the technology still used in thermometers today.
Modern thermometers are usually either mercury-based, infrared, or digital. Mercury thermometers were once the most popular type, but they are being phased out as mercury is poisonous and is, therefore, a danger if the thermometer breaks.
Mercury thermometers work by the outer material touching the mercury inside the glass and conducting heat energy to it. The mercury then expands as it becomes liquid and rises up the tube to the correct temperature.
Digital thermometers use an electronic chip that recognises temperature changes. The chip then checks the pressure against an internal resistor and converts this into a temperature reading.
Infrared thermometers detect radiation from surrounding objects that is caused by the molecules inside the objects moving. The higher the temperature, the faster the molecules move and the more radiation they emit. The radiation is measured, and the thermometer converts it into a temperature reading.
Barometers
Barometers are used to measure atmospheric pressure. Atmospheric pressure readings can then be used to predict changes in the weather, so barometers are crucial to weather forecasting.
A high reading on a barometer indicates high pressure, which is interpreted as a sign of good weather on the horizon. A low reading usually forecasts bad weather coming.
The first barometer was created in the 17th century by an inventor called Evangelista Torricelli. He used a water tube to conduct experiments related to air pressure shifts and weather forecasting.
Like thermometers, barometers use mercury to provide pressure readings. The barometer acts like a set of scales that balances the weight and density of the atmosphere with the mercury within the barometer. If the air pressure is high, the mercury rises. If it is low, it falls.
Hygrometer
Hygrometers are used for measuring humidity. They measure the amount of water vapour in the air and then combine this with other readings of temperature and pressure to provide an accurate measurement of humidity levels.
Early hygrometers were invented in Ancient China. They used a lump of charcoal and a lump of earth and measured the weight of both when dry compared with their weights after exposure to the air. The differences in weight were then used to estimate the levels of humidity.
Centuries later, in 1480, Leonardo da Vinci created developed another proto-hygrometer before an early variant of the modern version was invented by the Swiss inventor Johann Heinrich Lambert in 1755.
Hygrometers work by using a process known as evaporative cooling. As water evaporates from a surface, the surface becomes cold as the water molecules absorb heat from it during the process. A hygrometer uses two thermometers, one with a wet bulb and the other with a dry bulb. If the water in the air evaporates fast, then the wet bulb temperature will drop. The humidity level is then taken by subtracting the wet bulb temperature from the dry bulb's.
Anemometer
Anemometers are used to measure wind speed. They use simple technology that is based around an internal spinning wheel. The stronger the wind, the faster the wheel spins. The anemometer counts the number of rotations within a time frame and converts that reading into a wind speed.
Anemometers have been used since Leon Battista Alberti invented the first one in 1450. Since their initial creation, the technology behind them has changed very little, though there are several different types of anemometers.
The placement of the anemometer is crucial, especially with regard to height and coverage. The higher the placement, the stronger the wind reading. Also, if there are trees or buildings surrounding the anemometer, the wind is likely to be blocked, and the reading will be lower.
The standard placement height for an anemometer is 10 metres off the ground.
Rain gauge
Rain gauges measure liquid precipitation over a set time period.
The first recorded rainfall records were in Ancient Greece in around 500 BC. In India, around 400 BC, rainfall was measured and used to predict crop growth and rain production. However, rainfall was likely recorded in other ways prior to these dates, but the records have not lasted.
In the modern world, there are different types of rain gauges. The US standard uses a cylinder within a container. If the cylinder fills, the overflowing water is kept within the container, and both measurements are taken.
The technology behind rain gauges has not changed much since their first use. They are so simple that you can even make your own rain gauge to keep in your garden.
Windsock
Windsocks - sometimes known as "wind cones" - are devices used to measure general wind speed and direction.
The name comes from the fact that a windsock is a large conical tube that looks like a very big sock. A windsock cannot measure the specific speed or direction of the wind, but it can be used as a basic indicator of both.
You may have seen windsocks at airports, where they are used on runways to show pilots the direction and strength of the wind. They are also occasionally used on roads subjected to particularly windy conditions.
The wind direction is indicated by the direction the windsock is pointing. However, wind directions are usually referred to as the compass point the wind originates from - so a windsock blowing north would be called a southerly wind.
The wind speed is indicated by the angle of the windsock in relation to the pole it is flying from. If the speed is low, the sock will droop. If it is high, the sock will fly horizontally.
Wind vane/weather vane/weathercock
Weather vanes are the quintessential weather measurement that most people think of when (if ever) they think of weather measurement.
Weather show which direction the wind is blowing but are often used for ornamental and decorative purposes. They often feature a cockerel design with fixed letters N, E, S, and W, that represent North, East, South, and West.
Weather vanes have been around for millennia, with the oldest textual reference dating back to China in around 139 BC. There are also noted mentions of weather vanes in Ancient Greece from around 50 BC.
In the 6th century AD, Pope Gregory I wrote that the rooster was the most suitable emblem of Christianity as Jesus had said that Peter would deny him three times before the rooster crows.
Since then, the rooster (or cockerel) has gradually become the standard symbol atop weather vanes, and in the 9th century, Pope Nicholas decreed that every church have one on its steeple.
Pyranometer
Pyranometers are used for measuring solar radiation. The name "pyranometer" is derived from the Greek words "pyr" meaning "fire," and "ano" meaning "above, sky."
Pyranometers were traditionally used for climatic research. However, recent interest in solar energy has meant that they are increasingly used for finding areas with high levels of solar radiance. These areas are ideal for erecting solar panels that can be used as a renewable energy source.
Measuring the weather is a fundamental part of creating weather forecasts and gathering long-term weather data to observe changes in the climate. Humans have measured weather in various forms for millennia, and while there have been advancements in some areas, others have stayed roughly similar to their antecedents.
Weather measurements allow us to plan for the future and adapt to whatever may be coming. The data the measurements provide means we can preemptively evacuate dangerous areas, lay grit on icy roads, and save food for poor harvests. While there is no changing the weather, our ingenuity has allowed us to understand it and prepare as best we can for whatever it may bring.
