Scientific Instruments

An Altimeter, sometimes called a height meter, is a tool designed to measure the height of the land surface or an object, such as an aircraft. The height refers to the distance above the sea. In aviation, an altimeter is important to show how a plane flies. The basic function of an Altimeter is to estimate the height, an important piece of information for navigation, especially in mountainous area or during flight.

An altimeter is not limited to aircraft. They are also useful for outdoor enthusiasts like, bikers and Kickers who will track the height change. Knowing the height can help with orientation, navigation and safety, especially when combined with map reading skills.

How Does an Altimeter Work?

Illustration by Steve Karp

Most altimeters used in aviation are barometric. This means that they measure the height by calculating air pressure in a particular place. The principle is simple: when the height increases, the atmospheric pressure decreases. An altimeter aboard an aircraft is essentially a pressure gauge connected to the pitot-static system. It receives pressure from the outside environment, which the pilots use to determine altitude.

Depending on how they operate, altimeters can be classified into several types:

• Barometric Altimeter: Uses air pressure to calculate altitude.
• Radar Altimeter: Using radio waves, measures the height of a plane over the area.
• GNSS Altimeter: uses Satellite signals to determine the height.

What is a barometer?

A barometer is a scientific device that measures atmospheric or air pressure. It is a crucial tool in meteorology, used for evaluating and predicting weather patterns. The atmosphere, the air layers around the earth puts under pressure due to gravity, which draws the air molecules towards the surface. This pressure is what a barometer measures. Barometers are required for weather forecasts. Since air pressure changes often lead to changes in shifts in the weather, such as storms, tornadoes, or storm approaches, barometers help researchers to monitor and predict these changes.  A barometer measures atmospheric pressure in units such as atmospheres or bars.

How Does a Barometer Work?

Barometers come in different types, but the two main categories are:

• Mercury Barometer: Balances the weight of mercury in a glass tube against the atmospheric pressure. When air pressure drops, the mercury level falls.
• Aneroid Barometer: Uses a small, flexible metal box that expands or contracts with changes in air pressure, moving a needle on a dial.

Barometers must be calibrated and kept at a constant level for accurate readings.

Key Differences Between Altimeter and Barometer

While altimeters and barometers are pressure-measuring devices, their functions and applications are distinct. Here is a detailed comparison:

Function

• Altimeter: Estimates how high you are above sea level using air pressure readings.
• Barometer: Measures the atmospheric pressure at a specific location, which can indicate weather changes.
  

Working Mechanism

• Altimeter: In aircraft, the altimeter connects to the pitot-static system, using static pressure to calculate altitude. The reading changes as the aircraft climbs or descends.
• Barometer: In a mercury barometer, atmospheric pressure pushes on a reservoir of mercury, causing the mercury in a tube to rise or fall. Aneroid barometers use a metal box that flexes with pressure changes.
  

Use Cases

• Altimeter: Essential for pilots, mountaineers, and outdoor adventurers who need to know their elevation.
• Barometer: Vital for meteorologists and scientists tracking weather systems and atmospheric changes.

Altimeter and Barometer in Everyday Devices

Modern technology has integrated both altimeters and barometers into various devices, including watches and smartphones.

• Altimeter in a Watch: Measures atmospheric pressure to estimate altitude above sea level.
• Barometer in a Watch: Monitors ambient air pressure to detect weather changes, sometimes working with GPS for more accurate elevation readings.

Can a Barometer Be Used as an Altimeter?

Since both devices measure air pressure, a barometer can be adapted to function as an altimeter. The altimeter is essentially an evolved form of the barometer, calibrated to display altitude instead of pressure. This is why many outdoor watches combine both features, offering users the ability to track both altitude and weather changes.

Types of Altimeters and Barometers

Altimeter Types

• Barometric Altimeter: Most common, uses air pressure.
• Radar Altimeter: Used in aircraft, measures height above ground using radio waves.
• GNSS Altimeter: Uses satellite data for precise altitude.
  

Barometer Types

• Mercury Barometer: Traditional, uses mercury in a glass tube.
• Aneroid Barometer: More portable, uses a flexible metal box.
  

Importance in Different Fields

Aviation

• Altimeters are indispensable in aviation. Pilots rely on them to maintain safe flight levels, avoid obstacles, and ensure proper landing approaches. The technology used in altimeters has remained largely unchanged since the mid-20th century, highlighting its reliability and importance1.

Meteorology

• Barometers are the backbone of weather prediction. Rapid changes in atmospheric pressure can signal the onset of storms or other extreme weather events. Meteorologists use barometers to monitor these changes and issue warnings when necessary.

Outdoor Activities

• For hikers, climbers, and explorers, altimeters provide crucial information about elevation, which can be vital for navigation and safety. Barometers, often included in outdoor watches, help users anticipate weather changes, making them valuable tools for anyone venturing into the wilderness.

Summary

Altimeters and barometers are both essential instruments for measuring atmospheric pressure, but their purposes diverge. Altimeters are designed to measure altitude, making them indispensable for navigation in aviation and outdoor activities. Barometers, on the other hand, are fundamental to weather forecasting, helping scientists and meteorologists predict atmospheric changes that could lead to severe weather events.

Both instruments have evolved over time but remain crucial in their respective fields. Whether you are a pilot, a meteorologist, or an outdoor enthusiast, understanding the differences between an altimeter and a barometer can enhance your ability to navigate, predict weather, and stay safe.

 Frequently Asked Questions

Q) Can a barometer be used as an altimeter?
Yes, with proper calibration, a barometer can be used to measure altitude, as both instruments rely on atmospheric pressure readings.

Q) What is the difference between a radar altimeter and a barometric altimeter?
A radar altimeter measures height above terrain using radio waves, while a barometric altimeter calculates altitude above sea level using air pressure.

Q) Why are barometers important for weather forecasting?
Barometers detect changes in atmospheric pressure, which often precede weather changes. Sudden pressure drops can indicate storms or other severe weather events1.

Q) How do altimeters and barometers work in watches?
Altimeter functions in watches use air pressure to estimate altitude. Barometers in watches monitor ambient air pressure, sometimes using GPS for more accurate readings. 

Disclaimer

We have compiled the best available information from reputable research papers and credible internet sources. However, the content provided in this article is for informational purposes only and should not be construed as professional advice. We strongly recommend that you conduct your own research and consult with qualified professionals before implementing any changes or making decisions based on the information presented.

Explore high-quality scientific instruments at Uniglobal Business. Visit our IndiaMART page for more products!