Altimeter

The altimeter meaning can be expressed as a device that measures height. An altimeter is used to measure the site’s distance above sea level. Altimeters are crucial navigational equipment for aeroplane and spacecraft pilots who need to keep track of their altitude above the Earth’s surface. Skydivers and mountaineers also use altimeters to determine their location in the sky or on the ground.

The majority of altimeters are barometric. For instance, they can estimate the air pressure at a location and calculate the height. As a person climbs higher a height, the air pressure drops.

This is because the air density is lower (thinner) at higher elevations. It puts less pressure on the Earth below.

The Need for An Altimeter

As a result, every 27 feet (8.23 m) above sea level, air pressure drops by around a millibar, which is a unit of pressure measured in inches of mercury. A barometer can be used as an altimeter in this way. A device that uses a more modern aneroid barometer or even mercury is not completely accurate, especially at higher altitudes, because it is dependent on air pressure changing uniformly with increasing elevation. A radar altimeter is utilised in high-altitude aircraft applications and in any sector where great precision is needed.

An altimeter is of utmost importance for pilots to understand the height they’re flying; they can always look out the windows! However, a pilot’s altitude (height above sea level) is far more crucial than you may assume. Some of the world’s mountain ranges are unexpectedly tall and difficult to notice in inclement weather. For example, Mount Everest is 8.8 kilometres (5.5 miles) above sea level, so flying above 10,000 metres (6.2 miles) doesn’t allow you much space to manoeuvre.

The transit time of a radio wave between a target and an aeroplane or satellite is measured using a high-precision radar altimeter. This enables high altitude readings and a level of precision that is hard to achieve with barometer-based sensors. Radar-based systems can also precisely estimate the heights of natural features such as mountains and ocean waves.

Radar altimetry has been used to confirm the occurrence of unusual “freak waves,” which are ocean waves that are several times higher than normal. They’re also utilised in various kinds of aviation navigation, and they help pilots land their planes safely. This technology has also been used to measure the world’s highest peaks precisely.

When travelling mountainous terrains, altimeters are handy for knowing your height and tracking elevation changes. They’re navigation equipment for plane and spaceship pilots who need to know how high they are above the earth’s surface.

The measurements on an altimeter alter as the elevation varies. Denali, Alaska, has roughly half the atmospheric pressure of Honolulu, Hawaii. Denali, commonly known as Mount McKinley, is North America’s tallest mountain. Honolulu is a sea-level city.

What Factors Affect The Measurements of an Altimeter?

Weather can significantly affect altitude readings since air pressure drops during storms.

A basic barometric altimeter consists of a sealed metal chamber, a spring, and a pointer that displays altitude in metres or feet. The chamber expands and contracts as air pressure drops and rises, bending the spring and moving the pointer. An altimeter can be attached to the instrument panel of an aircraft or worn on a person’s wrist.

What is the significance of an altimeter for measuring altitude?

An altimeter is of utmost importance for pilots to know how high they’re flying; after all, they can always look out the windows! However, a pilot’s altitude (height above sea level) is far more crucial than you may assume. Some of the world’s mountain ranges are unexpectedly tall and difficult to notice in inclement weather. For example, Mount Everest is 8.8 kilometres (5.5 miles) above sea level, so flying above 10,000 metres (6.2 miles) doesn’t allow you much space to manoeuvre.

Other Types of Altimeters 

Altimeters are divided into four categories:

• A barometric altimeter

• Radio Altimeter

• GNSS (Global Navigation Satellite System)

• Laser Altimeter

Air pressure isn’t required for all altimeters. By triangulating signals from several satellites, the Global Positioning System (GPS), for example, may offer height as part of an area’s position.

Some aeroplanes and spacecraft include radar and laser altimeters, which perform similarly to sonar readings of the seabed. These altimeters emit a radio or laser signal toward the surface and how long it takes for the signal to return. The time it takes for the signal to return to the aircraft (or echo) is converted to an elevation.

Radar and laser altimeters can combine altitude readings to generate precise topographic images of both land and ocean surfaces when employed in satellites. For instance, the surface topography of 95 percent of the ice-free ocean was measured by the radar altimeter onboard the TOPEX/Poseidon satellite. TOPEX/radar Poseidon altimeter, developed by NASA and CNES, the French space agency, was accurate to within 2 centimetres (less than 1 inch)! TOPEX/Poseidon, in conjunction with another satellite, Jason-1, plotted the rise in worldwide sea levels, demonstrating the link between global climate change and sea-level rise.

What is the difference between an altimeter and a barometer?

Both the altimeter and the barometer are used to determine pressure. For instance, they calculate air pressure at a given area to determine the height. Weather patterns produce variations in elevation and changes in air pressure, which are measured by barometers.

Conclusion

A device that measures height – an altimeter – calculates the distance of the height above the sea level.  At various levels, altimeters can be used to match the relevant air pressure to the height. In aeroplanes, altimeters are used to indicate pressure altitude above sea level. Thus, as the height changes or the elevation changes, the measurements of an altimeter changes. Also, weather patterns cause changes in elevation and air pressure, monitored by barometers.