In basic physics and weather science, which instrument is specifically used to measure atmospheric air pressure?

Introduction / Context:
Measuring air pressure is essential in physics, meteorology and everyday weather forecasting. Atmospheric pressure influences wind patterns, cloud formation and storm systems. Instruments that measure this pressure help meteorologists predict weather changes and allow scientists to study the behaviour of gases. This question checks whether you can correctly identify the standard instrument used to measure atmospheric air pressure from a list of scientific devices.

Given Data / Assumptions:

• We are dealing with atmospheric air pressure, not pressure in a laboratory gas container.
• The options include several scientific instruments commonly mentioned in physics.
• Each instrument has a specific and different purpose.
• We assume normal school level definitions of these devices.

Concept / Approach:
The instrument that is traditionally and most widely used to measure atmospheric air pressure is the barometer. A barometer may be of mercury type, aneroid type or digital type, but its primary function remains the same, to give a reading of the surrounding air pressure. A manometer is related but is mainly used for measuring gas or liquid pressure in closed systems, such as pressure inside a tank or pipeline. A spectrometer is used to analyse light spectra and identify elements or compounds. A bolometer measures the power of incident electromagnetic radiation, often in infrared astronomy. Therefore the only option that directly matches atmospheric air pressure measurement is the barometer.

Step-by-Step Solution:
Step 1: Focus on the phrase atmospheric air pressure in the question.Step 2: Recall that weather reports often mention barometric pressure, meaning pressure measured by a barometer.Step 3: Match barometer with air pressure measurement used in meteorological stations and laboratories.Step 4: Recognise that a manometer usually measures pressure differences in gases or liquids confined in tubes or vessels.Step 5: Recall that a spectrometer deals with light spectra and is not a pressure measuring device.Step 6: Note that a bolometer is used to measure the power of incoming radiation, not air pressure.Step 7: Conclude that barometer is the only correct answer.

Verification / Alternative check:
In weather charts and instruments, barometric pressure is usually recorded in units such as millibars or hectopascals. The barometer reading helps to identify high pressure and low pressure systems that drive weather changes. Textbooks and general knowledge references describe a barometer specifically as an instrument for measuring atmospheric pressure. Manometers are shown as U shaped tubes to compare pressures of gases or liquids, and spectrometers are drawn as optical devices splitting light into bands. These descriptions confirm that barometer is the correct choice for measuring air pressure around us.

Why Other Options Are Wrong:
Manometer measures pressure in closed systems, not typically open atmospheric pressure as in weather observations. Spectrometer is used to study the spectrum of light and to analyse the composition of substances, not to measure pressure. Bolometer measures the power of electromagnetic radiation, often in research applications, and has no direct role in routine air pressure measurements.

Common Pitfalls:
Students sometimes confuse barometer and manometer because both relate to pressure. The key difference is that barometers are designed for atmospheric pressure, whereas manometers are used for relative or gauge pressure in controlled systems. Others may choose spectrometer simply because the name sounds technical. To avoid errors, remember barometer for barometric or atmospheric pressure and manometer for gas pressure in pipes and vessels.

Final Answer:
The instrument that measures atmospheric air pressure is the barometer.