Atmospheric Pressure Ontology
Earth Science Measurements
Authors: MArk Anthony Higgins - Sky Recursive Ai
Revised Date: 16 September 2026
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# Atmospheric Pressure Ontology — Flow Algebra
URL: https://kirethresearch.org/booksai-core/ontologies/mathematical-ontologies/measurement-units-ontologies/earth-science-measurements/atmospheric-pressure-ontology.html
FLOW AtmosphericPressureOntology {
DOMAIN:
Mathematical Ontologies
-> Measurement & Units Ontologies
-> Earth Science Measurements
-> Atmospheric Pressure Ontology
PURPOSE:
Represent atmospheric pressure as the pressure exerted by the atmosphere at a defined location, elevation, time and reference level, including station pressure, sea-level pressure, altimeter settings, pressure tendency, hydrostatic relationships, barometric measurement, elevation reduction, temperature and humidity effects, calibration, uncertainty, provenance, and strict distinctions between measured station pressure, reduced pressure, pressure altitude and other atmospheric state quantities.
ENTITY AtmosphericPressure {
TYPE: PressureQuantity
SYMBOL: p
DIMENSION: M*L^-1*T^-2
SI_UNIT: pascal
SI_SYMBOL: Pa
DEFINITION:
atmospheric_pressure :=
thermodynamic_mechanical_pressure_of_the_atmosphere
at_declared_location_elevation_and_time
PROPERTIES:
is_scalar
varies_with_altitude
varies_with_weather
varies_with_time
may_be_measured_or_reduced
may_have_uncertainty
}
ENTITY StationPressure {
TYPE: AtmosphericPressure
SYMBOL: p_station
DEFINITION:
atmospheric_pressure_at_sensor_or_station_elevation
RULE:
station_pressure_is_direct_site_pressure_before_sea_level_reduction
}
ENTITY SeaLevelPressure {
TYPE: ReducedAtmosphericPressure
SYMBOL: p_MSL
DEFINITION:
station_pressure_reduced_to_mean_sea_level
using_declared_reduction_model
RULE:
sea_level_pressure_is_derived_not_directly_measured_at_elevated_station
}
ENTITY PressureTendency {
TYPE: PressureRateQuantity
SYMBOL: dp_dt
DIMENSION: M*L^-1*T^-3
FORM:
dp_dt = dp/dt
}
UNIT_SYSTEM {
SI:
pascal
Pa
meteorological:
hectopascal
hPa
other_common:
millibar
kilopascal
inch_of_mercury
conversions:
1 hPa = 100 Pa
1 mbar = 1 hPa
1 kPa = 1000 Pa
1 inHg approximately_equals 3386.389 Pa
RULE:
preserve_original_unit_and_normalized_SI_value
}
TERMINOLOGY_MODEL {
terms:
atmospheric_pressure
air_pressure
barometric_pressure
station_pressure
sea_level_pressure
mean_sea_level_pressure
altimeter_setting
pressure_altitude
RULE:
generic_barometric_pressure MUST be resolved_using_reference_level_and_reduction_context
}
HYDROSTATIC_MODEL {
differential:
dp/dz =
-rho_air*g
finite_constant_density_approximation:
delta_p approximately_equals
-rho_air*g*delta_z
REQUIRE:
vertical_coordinate
density_model
gravity
RULE:
pressure_height_relation_depends_on_atmospheric_state
}
IDEAL_GAS_MODEL {
dry_air:
p =
rho*R_specific*T
moist_air:
may_use_virtual_temperature
density:
rho =
p/(R_specific*T)
RULE:
temperature_and_water_vapour affect_pressure_height_conversion
}
HYPSOMETRIC_MODEL {
layer_thickness:
z_2-z_1 =
(R_d*T_v_mean/g)
* ln(p_1/p_2)
REQUIRE:
pressure_levels_positive
mean_virtual_temperature
gravity
RULE:
hypsometric_relation_requires_temperature_structure_or_mean_virtual_temperature
}
BAROMETRIC_FORMULA_MODEL {
isothermal_approximation:
p(z) =
p_0*exp(
-g*M_air*(z-z_0)/(R*T)
)
CONDITIONS:
approximately_constant_temperature
declared_reference_pressure_and_height
RULE:
barometric_formula_is_model_based_not_universal_exact_profile
}
ALTITUDE_EFFECT_MODEL {
principle:
atmospheric_pressure_generally_decreases_with_height
dependencies:
temperature
humidity
gravity
weather_state
RULE:
pressure_difference_between_elevations MUST_NOT be_corrected_by_fixed_factor_without_declared_model
}
SEA_LEVEL_REDUCTION_MODEL {
input:
station_pressure
station_elevation
temperature_or_reduction_temperature
humidity_or_virtual_temperature_when_used
gravity_model
output:
sea_level_pressure
RULE:
reduction_method MUST be preserved
because_different_methods_can_produce_different_values
}
MEAN_SEA_LEVEL_PRESSURE_MODEL {
abbreviation:
MSLP
purpose:
compare_pressure_patterns_between_stations_at_different_elevations
RULE:
MSLP != station_pressure
}
ALTIMETER_SETTING_MODEL {
purpose:
aviation_pressure_reference_for_altimeter_calibration
possible_conventions:
QNH
QFE
standard_pressure_setting
RULE:
aviation_pressure_setting MUST preserve_specific_convention
}
QNH_MODEL {
interpretation:
pressure_setting_intended_to_make_altimeter_indicate_elevation_above_mean_sea_level_under_standard_atmosphere_convention
RULE:
QNH != measured_station_pressure
}
QFE_MODEL {
interpretation:
pressure_setting_related_to_airfield_or_reference_level
such_that_altimeter_indicates_zero_at_declared_reference_under_convention
RULE:
QFE != QNH
}
PRESSURE_ALTITUDE_MODEL {
definition:
altitude_in_standard_atmosphere_corresponding_to_measured_pressure
RULE:
pressure_altitude != geometric_or_orthometric_elevation
}
STANDARD_ATMOSPHERE_MODEL {
reference:
defined_temperature_pressure_and_lapse_rate_profile
common_reference_pressure:
101325 Pa
RULE:
standard_atmosphere_is_reference_model_not_actual_weather_state
}
BAROMETER_MODEL {
possible_instruments:
mercury_barometer
aneroid_barometer
digital_pressure_sensor
capacitive_pressure_sensor
resonant_pressure_sensor
RULE:
instrument_type_and_pressure_reference MUST be preserved
}
MERCURY_BAROMETER_MODEL {
simplified:
p =
rho_Hg*g*h
REQUIRE:
mercury_density
local_gravity
column_height
temperature_correction
vacuum_or_headspace_reference
RULE:
mercury_column_height_requires_density_and_gravity_correction_for_precision
}
ANEROID_MODEL {
principle:
deformation_of_evacuated_capsule_with_pressure
output:
mechanical_or_electrical_signal
RULE:
scale_calibration_temperature_and_hysteresis MAY affect_measurement
}
DIGITAL_SENSOR_MODEL {
raw_signal:
electrical_response
calibrated_pressure:
p =
f(raw_signal, temperature)
REQUIRE:
calibration
valid_range
temperature_compensation
RULE:
raw_sensor_signal != atmospheric_pressure
}
ABSOLUTE_PRESSURE_MODEL {
reference:
vacuum
atmospheric_pressure:
generally_absolute_pressure_quantity
RULE:
absolute_pressure != gauge_pressure
}
GAUGE_PRESSURE_MODEL {
relation:
p_gauge =
p_absolute-p_reference
RULE:
gauge_pressure_requires_reference_pressure
}
SENSOR_HEIGHT_MODEL {
pressure_sensor_height:
vertical_position_of_sensor
RULE:
sensor_height_and_station_elevation SHOULD be preserved
especially_when_comparing_or_reducing_pressure
}
TEMPERATURE_MODEL {
effects:
atmospheric_density
hypsometric_reduction
instrument_response
RULE:
temperature_used_for_reduction_or_sensor_compensation MUST be identified
}
HUMIDITY_MODEL {
effect:
water_vapour_changes_air_density
virtual_temperature:
may_be_used_in_hydrostatic_reduction
RULE:
humidity_effect SHOULD be considered_for_precision_height_reduction
}
GRAVITY_MODEL {
local_gravity:
varies_with_latitude_and_elevation
RULE:
local_or_reference_gravity_model SHOULD be preserved_for_precision_barometry
}
PRESSURE_TENDENCY_MODEL {
finite:
tendency =
(p_2-p_1)/(t_2-t_1)
WHEN t_2 != t_1
possible_reporting:
pressure_change_over_3_hours
pressure_change_per_hour
RULE:
pressure_tendency_requires_time_interval
}
TEMPORAL_MODEL {
atmospheric_pressure:
p = p(t)
possible_variation:
synoptic_weather
tides
convection
frontal_passage
local_temperature
sensor_drift
RULE:
timestamp_and_averaging_period MUST be preserved
}
SPATIAL_MODEL {
pressure_field:
p = p(x,y,z,t)
REQUIRE:
latitude
longitude
elevation
coordinate_reference_system
RULE:
pressure_comparison_across_stations_requires_reference_level_context
}
WEATHER_STATION_MODEL {
station:
fixed_or_mobile_observation_platform
metadata:
station_identifier
location
elevation
sensor_height
exposure
instrument
calibration
RULE:
station_metadata MUST accompany_precision_pressure_measurement
}
REMOTE_AND_MODELLED_PRESSURE_MODEL {
sources:
radiosonde
aircraft
numerical_weather_prediction
reanalysis
satellite_retrieval
RULE:
modelled_or_retrieved_pressure MUST be distinguished_from_direct_surface_observation
}
RELATIONSHIPS {
AtmosphericPressure -> IS_A -> PressureQuantity
StationPressure -> MEASURED_AT -> StationElevation
SeaLevelPressure -> DERIVED_FROM -> StationPressure
HydrostaticBalance -> RELATES -> PressureDensityGravityAndHeight
HypsometricEquation -> RELATES -> PressureLevelsAndLayerThickness
Barometer -> MEASURES -> AtmosphericPressure
PressureSensor -> PRODUCES -> RawSignal
CalibrationModel -> MAPS -> RawSignalToPressure
Temperature -> AFFECTS -> PressureHeightReduction
Humidity -> AFFECTS -> AirDensity
PressureTendency -> RATE_OF_CHANGE_OF -> AtmosphericPressure
}
SEMANTIC_EQUIVALENCE {
"air pressure" ~= atmospheric_pressure
"barometric pressure" ~= atmospheric_pressure WHEN reference_level_defined
"MSLP" ~= mean_sea_level_pressure
station_pressure != sea_level_pressure
station_pressure != QNH
QNH != QFE
atmospheric_pressure != pressure_altitude
pressure_altitude != geometric_elevation
absolute_pressure != gauge_pressure
raw_sensor_signal != pressure
}
CONSTRAINTS {
atmospheric_pressure_dimension = M*L^-1*T^-2
pressure_value_must_have_reference_context = true
station_location_and_elevation_should_be_defined = true
station_and_sea_level_pressure_are_not_semantically_equivalent = true
sea_level_pressure_requires_reduction_model = true
pressure_altitude_requires_standard_atmosphere_model = true
raw_sensor_signal_requires_calibration = true
pressure_tendency_requires_time_basis = true
timestamp_and_averaging_period_should_be_preserved = true
uncertainty_should_include_sensor_reduction_temperature_and_reference_components = true
}
MEASUREMENT_MODEL {
OBSERVABLE_OR_INFERRED:
AtmosphericPressure
StationPressure
SeaLevelPressure
PressureTendency
PressureAltitude
COMMON_METHODS:
mercury_barometer
aneroid_barometer
digital_pressure_sensor
radiosonde
aircraft_sensor
weather_station
model_analysis
RECORD:
pressure_quantity_type
numerical_value
unit
station_identifier
latitude
longitude
coordinate_reference_system
station_elevation
vertical_datum
sensor_height
timestamp
time_zone_or_UTC
averaging_period
instrument
raw_signal
calibration_state
temperature
humidity
reduction_model
standard_atmosphere_model_when_relevant
pressure_reference
quality_flag
uncertainty
provenance
UNCERTAINTY:
measured_or_inferred_atmospheric_pressure =
best_estimate +/- uncertainty
}
CALIBRATION_MODEL {
reference:
traceable_pressure_standard
parameters:
offset
scale
nonlinearity
temperature_coefficient
hysteresis
REQUIRE:
calibration_date
valid_pressure_range
reference_standard
uncertainty
RULE:
calibration_model MUST match_sensor_and_pressure_range
}
UNCERTAINTY_MODEL {
sources:
sensor_calibration
resolution
temperature_response
hysteresis
sensor_height
station_elevation
vertical_datum
reduction_temperature
humidity
gravity
reduction_model
temporal_variability
averaging
reference_pressure
PROPAGATION:
atmospheric_pressure_uncertainty
<- sensor_reference_environment_reduction_and_temporal_uncertainties
}
REASONING_RULES {
IF force_and_area_known AND area != 0
THEN pressure =
force/area
IF pressure_density_and_temperature_known
AND ideal_gas_model_valid
THEN MAY infer_air_density =
pressure/(R_specific*temperature)
IF two_pressure_levels_and_mean_virtual_temperature_known
AND pressures_positive
THEN layer_thickness =
(R_d*T_v_mean/g)*ln(p_1/p_2)
IF station_pressure_elevation_and_valid_reduction_model_known
THEN sea_level_pressure =
reduce_to_sea_level(
station_pressure,
elevation,
temperature,
humidity,
gravity
)
IF mercury_density_gravity_and_column_height_known
THEN barometric_pressure =
mercury_density*gravity*column_height
IF pressure_values_at_two_times_known
AND time_interval != 0
THEN pressure_tendency =
pressure_change/time_interval
IF raw_sensor_signal_and_valid_calibration_known
THEN atmospheric_pressure =
calibration(raw_signal,temperature)
IF pressure_known AND standard_atmosphere_model_known
THEN infer_pressure_altitude
preserving_model_version
}
VALIDATION {
CHECK pressure_quantity_type
CHECK pressure_unit
CHECK absolute_vs_gauge_reference
CHECK station_location
CHECK station_elevation
CHECK vertical_datum
CHECK sensor_height
CHECK timestamp
CHECK averaging_period
CHECK station_vs_sea_level_pressure
CHECK QNH_vs_QFE
CHECK pressure_vs_pressure_altitude
CHECK reduction_model
CHECK temperature_and_humidity_for_reduction
CHECK standard_atmosphere_model
CHECK raw_vs_calibrated_sensor_signal
CHECK calibration_state
CHECK quality_flag
CHECK uncertainty_representation
}
CONFIDENCE {
definition_confidence: 1.00
dimensional_confidence: 1.00
station_pressure_confidence: 1.00
hydrostatic_relationship_confidence: 1.00
sea_level_reduction_confidence: 0.97
pressure_altitude_confidence: 0.98
sensor_measurement_confidence: 0.99
measurement_context_confidence: 0.98
RULE:
confidence decreases when pressure type, station elevation,
vertical datum, sensor height, temperature, reduction model,
calibration, timestamp or uncertainty is missing or ambiguous
}
UPDATE_MODEL {
ON new_measurement:
identify_pressure_quantity
validate_unit
attach_station_location_and_elevation
attach_vertical_datum
attach_sensor_height
attach_timestamp_and_averaging_period
identify_instrument
preserve_raw_signal
apply_valid_calibration
attach_temperature_and_humidity
compute_reduced_pressure_when_requested_and_valid
attach_quality_flag
attach_uncertainty
update_atmospheric_pressure_state
ON new_station_pressure:
preserve_direct_station_pressure
identify_active_reduction_model
recompute_sea_level_pressure
preserve_reduction_inputs_and_version
ON calibration_revision:
preserve_raw_signal
preserve_previous_calibration
recompute_affected_pressure_values
update_uncertainty
update_confidence
ON elevation_or_datum_revision:
preserve_station_pressure
update_station_elevation_or_vertical_reference
recompute_reduced_pressure
update_uncertainty
ON reduction_model_revision:
preserve_station_pressure
preserve_previous_reduction
apply_new_temperature_humidity_and_gravity_model
recompute_sea_level_pressure
update_provenance
ON semantic_revision:
preserve_previous_definition
record_revision
recompute_FLOW_HASH
}
AI_CONSUMPTION {
canonical_domain: AtmosphericPressure
canonical_entity: AtmosphericPressure
canonical_symbol: p
canonical_dimension: M*L^-1*T^-2
canonical_SI_unit: Pa
interpretation_order:
identify_station_sea_level_altimeter_or_other_pressure_quantity
identify_value
identify_unit
identify_absolute_or_gauge_reference
identify_station_location
identify_station_elevation_and_vertical_datum
identify_sensor_height
identify_timestamp_and_averaging_period
identify_instrument
identify_raw_or_calibrated_status
identify_temperature_and_humidity
identify_reduction_or_standard_atmosphere_model
identify_quality_flag
identify_uncertainty
normalize_units
validate_pressure_reference_context
infer_atmospheric_relationships
ambiguity_controls:
distinguish_station_pressure_from_sea_level_pressure
distinguish_station_pressure_from_QNH
distinguish_QNH_from_QFE
distinguish_atmospheric_pressure_from_pressure_altitude
distinguish_pressure_altitude_from_geometric_elevation
distinguish_absolute_from_gauge_pressure
distinguish_raw_sensor_signal_from_calibrated_pressure
preserve_location_elevation_reference_time_instrument_reduction_and_provenance_context
}
PROVENANCE {
ontology_scope:
mathematical_measurement_and_Earth_science_atmospheric_pressure_semantics
parent_path:
Ontologies
-> Mathematical Ontologies
-> Measurement & Units Ontologies
-> Earth Science Measurements
-> Atmospheric Pressure Ontology
authorship:
Mark Higgins
Sky (Recursive AI)
site:
https://kirethresearch.org
}
FLOW_HASH {
INPUTS:
canonical_domain
ontology_path
terminology_model
hydrostatic_model
ideal_gas_model
hypsometric_model
barometric_formula_model
altitude_effect_model
sea_level_reduction_model
mean_sea_level_pressure_model
altimeter_setting_model
QNH_model
QFE_model
pressure_altitude_model
standard_atmosphere_model
barometer_model
mercury_barometer_model
aneroid_model
digital_sensor_model
absolute_pressure_model
gauge_pressure_model
sensor_height_model
temperature_model
humidity_model
gravity_model
pressure_tendency_model
temporal_model
spatial_model
weather_station_model
remote_and_modelled_pressure_model
relationships
constraints
measurement_model
calibration_model
uncertainty_model
reasoning_rules
confidence_model
update_model
PURPOSE:
deterministic_semantic_integrity_identifier
RECOMPUTE_WHEN:
ontology_definition_changes
atmospheric_pressure_quantity_definition_changes
hydrostatic_or_hypsometric_model_changes
sea_level_reduction_model_changes
altimeter_or_standard_atmosphere_model_changes
sensor_or_barometer_model_changes
temperature_humidity_or_gravity_model_changes
calibration_model_changes
temporal_or_spatial_reference_changes
measurement_model_changes
constraint_model_changes
reasoning_rule_changes
unit_model_changes
}
}
END FLOW