Weather observations: what is it and how we do it

Weather observations are recordings and study of different states of the atmosphere, ocean and earth with the help of special tools and equipment on a daily basis or occasionally to produce more accurate weather forecasts.

Humans began observing the weather in an attempt to predict its behavior thousands of years ago. At first, knowledge of various weather phenomena was passed on by word of mouth — that’s how the weather lore came about. Then the exact air and sea temperature, amount of precipitation or wind speed was recorded and documented on paper. Today radar and satellites are used to do the same and the information is processed on supercomputers.

In this lesson of the Windy.app Meteorological Textbook for better weather forecasting you will learn what weather observations area, including their main types.

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There are many different types of weather observations. Some of them are organized by an observation network. They are performed regularly, and the information goes to data-collection centers and is then used to create forecasts. Some observations are performed for scientific purposes only.

Observations can also be made by contact or remotely.

An example of contact observation is a regular thermometer. It makes contact with air or water of a specific temperature, and becomes the same temperature itself. And it can somehow (usually through the expansion/compression of the liquid it contains) show this temperature.
Remote observations are a different story. During the pandemic, more than once you have dealt with a remote digital thermometer pointed to your forehead or e wrist which doesn’t touch your skin. This thermometer “collects” the infrared radiation from your body, and uses laws of physics to translate it into your body temperature. You might have also noticed that this measurement is less precise than measurements by a traditional thermometer.

Of course, the differences between different types of observation do not end here, but this is enough to get the gist of it. So, let’s dive in.

Weather stations

Weather stations are the most important source of observation data worldwide. At the beginning of the 19th century, a network of weather stations emerged in Europe. At that time, a big storm sank over 50 ships close to the Crimean shore. Investigating the tragedy, experts noticed that the storm had travelled several hundred kilometers across Europe. Had its route been traced on a map in advance, it would have become apparent that it would soon reach Crimea. This made it evident that a solid network for weather observation with international data exchange is necessary, and the faster this exchange is, the better. Nowadays, there are weather stations in practically every country, and they all have free access to each other’s data.

This is what an observation platform looks like. Nataliya Shestakova / Wikipedia

For the data to be comparable, all weather stations are organized in approximately the same way: they are in areas of land with the most typical characteristics for each zone. The devices are very similar, too. Pressure, temperature, humidity, clouds, precipitation and a few more parameters are observed by every one. Special stations also make additional, more specific, observations: for example, of solar activity or air quality. These observations are performed manually by actual observers in person.

However, equipping a proper weather station is very challenging and expensive. You need to find the land, and the people to measure everything... And what if it’s far away from civilization? There won’t be many people willing to work there. This is where automatic weather stations come in handy.

The automatic weather station “Davis” is one of the most popular in the world. It’s cheap and user-friendly. Cjp24 / Wikipedia

These facilities work based on energy from currents or batteries, and measure everything automatically, which is much more convenient. The quality of measurements at such stations is generally lower than the traditional ones, and some parameters that require direct observation (for example, atmospheric phenomena and clouds) are not registered at all. On the other hand, these stations can be out anywhere, and in any number.

Over time, as automatic weather stations develop, manned stations become less and less common. It’s the expected and natural evolution of the observation network. But we still can’t break completely free of traditional weather stations, because they are an example that has stood the test of time and is the standard of measurement for the other methods. Some weather stations carry out uninterrupted observations for several decades in a row. This data is of incredible value to science, and we can’t simply close them down.

Weather satellites

Weather stations are used for contact observations and satellite observations are used for remote ones: the most common and popular type. Satellites can perform all kinds of observations over any place on Earth, which is their huge advantage over other types of observation. Many meteorological discoveries (for example, polar cyclones) have been made only thanks to satellite photos.

Design project of a satellite for observations over the Arctic. European Space Agency / Wikipedia

Onboard satellites are sensors that register electromagnetic waves of different frequencies. Special programs or humans then analyze the resulting images. But unlike a regular camera that only records information within the visible range (that is, a photograph only shows what we can see with our eyes), satellites can take “pictures” at different frequencies. Different frequencies, in turn, can give us insights into various factors useful for weather forecasting. For example, visible radiation is used to determine cloudiness, ice in the ocean, and snow on the ground.

An example of a satellite photo of Japan within the visible range. The clouds in the lower part of the image are part of an atmospheric front. White spots on the island are snow in the mountains. Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC / Wikipedia

Infrared radiation tells us not only about the temperature of the air, the surface, and some wavelengths — it also tells us about the amount of water vapor in the atmosphere.

The main problem with the satellites is that they need to be calibrated from time to time, that is, to compare their data with the data of contact observations to make sure that all the settings are in order. Calibration is a tricky task in hard-to-reach areas. That’s why satellite data is not usually considered very reliable and is used only when there are no other sources of information.

Infrared image of a tropical cyclone. U.S. Navy / Wikipedia

Weather radars

Another popular method of remote observation is radar. Electromagnetic signals are sent into the atmosphere, which are reflected by different particles (for example, raindrops) and return. By observing the changes in the signal after its “trip”, you can understand which particles it came in contact with. And with that knowledge, you can make a precipitation map, or discover which clouds carry rain mixed with hail versus those which will only hold a light shower. The data from the radar is useful for weather forecasts, particularly for predicting precipitation.

Digital doppler weather radar near Thessaloniki Airport, Greece. Ipernity.com / Wikipedia

Weather buoys

Most information from the oceans comes to us from satellites, as contact observations can be a problem. But that doesn’t mean that they don’t exist. There are, for example, weather buoys. Essentially, they are automatic weather stations floating on the water, and they perform all of the main weather observations. Unfortunately, there are currently only about 1000 buoys in the observation network; for the vast ocean area, that is very few. Additionally, buoys are distributed very unevenly.

Weather buoy. Picture credit: NOAA / Unsplash

Weather ships

More advanced weather stations can be installed on ships. There are special ships for scientific research that are equipped with many devices, and have entire laboratories on board. Of course, such vessels can be counted on your fingers. Sometimes automatic weather stations are installed on ships with other primary purposes, for example, tankers. Their measurements, however, could be more precise.

Research vessel. NOAA / Unsplash

Weather balloons

Weather balloons are the main information source at altitudes of a few meters to 40 km. They are huge air balloons with boxes full of devices tied to them. Quite a view!

They measure the same parameters as weather stations: temperature, humidity, pressure and wind speed. The data from the devices is automatically transmitted to land. By the way, before the invention of the radio, there was no way to transmit information from the balloon to the ground. So scientists had to arrange for the dwellers in the surrounding villages to return the balloons they found for a small compensation. And that worked: most balloons came back.

Launch of a weather balloon. NOAA / Unsplash

Weather rockets

Weather rockets are one of the rarest means of observation currently in use. They are used for exploring the higher layers of the atmosphere, which the balloons can’t reach. A rocket is shot to a height of 100-120 km, after which a parachute opens and slowly lowers the equipment to the ground while performing the necessary measurements.

These measurements are exact, but very expensive, too. They were most popular in the 60s and 70s when the near-Earth space started to be explored. Nowadays, when all the most important measurements have been made already, rockets are launched rarely — only on special occasions. Their data is only used for scientific purposes.

Weather rocket. NOAA / Unsplash

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There are many other types of observations:

Giant zeppelins can hang over the ground at the same height for months.
Planes with meteorological devices can be directed right to the center of a storm.
Adventure-seeking amateurs, such as tornado and hurricane hunters.

Every observation is a source of valuable information, and the capabilities of modern devices and scientists’ knowledge sometimes makes an impression on our imagination. The future holds many new fascinating ways for us to explore the world!