Normalized Atmosphere

Professor: Rodolfo Morales Ibarra.

Team: 3

Team members:
Guillermo Jacobo López - 2043740
Valda Karyme Cisneros Flores - 2132214

Group: 003
 Altitude

Height above sea

level.
Geometric
Altitude
Actual vertical
height above sea
level.
 Absolute
Altitude
Height from the
center of the
earth.
Geopotential altitude
 What is geopotential altitude?
It is the height, referred to sea level, of a point in the atmosphere, expressed in units
proportional to the geopotential at said point, that is, to the work necessary to bring a unit
mass from sea level to that point.
It is expressed in geopotential meters (mgp), and the relation between geopotential and
geometric height is:
9.8×dZ=g×dz
● Z= Geopotential height
● z= Geometric height
● g= Gravity acceleration (9.8 m/s^2)
Geopotential altitude example
PRESSURE ALTITUDE
Aircraft pressure altimeters indicate the elevation
of the aircraft above a defined datum. The datum
selected depends on the barometric pressure set
on the altimeter sub-scale.
 Effects of Temperature on Altimeter Readings

Three references for barometric pressure are in common

usage: QNH, QFE and Standard Pressure.

● QNH. The altimeter sub-scale setting to obtain

elevation when on the ground.

● QFE. The atmospheric pressure at aerodrome

elevation (or at runway threshold).
TEMPERATURE ALTITUDE
 Once the boundary layer of the air adheres to the wing by
friction, further resistance to the airflow is caused by the
viscosity, the tendency of the air to stick to itself. When
these two forces act together to resist airflow over a wing, it is
called drag.

A standard temperature lapse rate is when

the temperature decreases at the rate of
approximately 3.5 °F or 2 °C per thousand
feet up to 36,000 feet, which is
approximately –65 °F or –55 °C.
DENSITY ALTITUDE
 What Is Density Altitude?

Density altitude is pressure altitude corrected for

nonstandard temperature. As temperature and altitude
increase, air density decreases. In a sense, it's the
altitude at which the airplane "feels" its flying.
 How Will High Density Altitude Affect Flight?

The less dense the air, the less lift,

the more lackluster the climb, and
the longer the distance needed for
takeoff and landing.

Fewer air molecules in a given

volume of air also result in
reduced propeller efficiency and
therefore reduced net thrust.
Calculating Density
Altitude
 ● Pressure altitude is determined by setting the altimeter to 29.92 and reading
the altitude indicated on the altimeter.
● OAT stands for outside air temperature (in degrees Celsius).
● ISA stands for standard temperature (in degrees Celsius).

Density altitude in feet = pressure altitude in feet + (120 x (OAT - ISA temperature))
Definition
A standard atmosphere, abbreviated atm,
is the unit of pressure equal to the average
atmospheric pressure at sea level.
Specifically 1 atm = 101,325 pascals, which is
the SI unit of pressure. When scientists refer
to STP (standard temperature and pressure),
this refers to a set of conditions for a system,
one of which is a pressure of 1 atm.
This is an important unit for describing gasses, as pressure is one of
the state variables that describe the gas in a heat engine.
Classification of the atmosphere

From lowest to highest, the major layers are

the troposphere, stratosphere, mesosphere,
thermosphere and exosphere.
Troposphere

Closest to the surface of Earth, we have the troposphere. “Tropos”

means change. This layer gets its name from the weather that is
constantly changing and mixing up the gases in this part of our
atmosphere.
stratosphere
Above the troposphere and below the mesosphere, we have the stratosphere. “Strat” means layer. This
layer of our atmosphere has its own set of layers.
Mesosphere
The mesosphere lies between the thermosphere and the stratosphere.
“Meso” means middle, and this is the highest layer of the atmosphere in
which the gases are all mixed up rather than being layered by their mass.
Thermosphere
The thermosphere lies between the exosphere and the mesosphere. “Thermo” means heat, and the
temperature in this layer can reach up to 4,500 degrees Fahrenheit.
Exosphere
The exosphere is the outermost layer of our atmosphere. “Exo” means outside and is the same prefix used to
describe insects like grasshoppers that have a hard shell or “exoskeleton” on the outside of their body.
Meteorological phenomena
 Turbulence
Turbulence is the small-scale and short-term chaotic movement of air particles. Sometimes it is just an
unpleasant phenomenon that causes the aircraft to shake, and sometimes it is much stronger and
more dangerous, so it can also cause a crash, primarily of light aircraft. Turbulence appears in clouds
and their vicinity, especially in thunderclouds.
 Aircraft icing
Ice can suddenly form on the wings of an aircraft, severely disrupting their aerodynamic properties and
causing the aircraft which can no longer fly to descend sharply.

Icing occurs due to the physical properties of the atmosphere in which water can exist in the form of water
droplets also at temperatures below 0°C.

The aircraft icing which occurs in that case can be extremely dangerous. Modern aircraft have ice protection
systems, but icing can still pose a threat, especially to light aircraft.
 Strong wind
Strong surface wind is especially dangerous during landing. In such situations, it is very difficult to align the
aircraft with the runway on landing, so pilots often have to make another landing attempt.

If the wind is so strong that it also causes strong turbulence, an additional problem arises, making it quite
difficult to stabilize the aircraft to land safely. Therefore, meteorologists pay special attention to such
situations, forecast them and forward the information to users.

Modern airlines take into account wind forecasts because this approach can significantly reduce flight duration
and costs.
 Wind shear
It occurs when winds of different speed or direction blow at different points which can be near each other.
Wind shear can be horizontal or vertical. In those situations, the aerodynamic flight parameters are abruptly
changed, so the aircraft climbs or stalls suddenly. If it is close to the ground when landing, this can be fatal.

Wind shear is also most dangerous when landing as it can cause a sudden drop of the aircraft.

Today, wind shear is forecasted and also detected by onboard or ground-based devices.
 Mountain waves
This occur when the air passes over an obstacle, such as a mountain. They appear behind the mountain in
the form of downdrafts and updrafts. It can also be visually accompanied by a cloud on the lee side of a
mountain.

Mountain waves are dangerous because the downdrafts that occur in them can make steering the aircraft
difficult, but they can also be useful because the updrafts can be used for flying and gaining altitude (gliders).
 Reduced visibility
Flying through clouds and fog, often means flying blind using navigational aids. But, today the issue of flying in
low visibility conditions is mostly solved by technology. It means flying under instrument flight rules when
various radio navigation aids are used for all phases of flight.

At airports, fog is the most significant issue. Meteorologists regularly forecast it and thus warn of possible
problems for regular air traffic. If all of the safety requirements are not met, flight operations can be suspended
due to fog.
 Thunderstorm
A thunderstorm is considered to be the most dangerous meteorological phenomenon for aviation.

It is dangerous for aircraft in the take-off or landing phase, but also for aircraft in the horizontal flight phase.

It can be caused by a single cloud or a cluster of clouds, which are called cumulonimbus clouds. They make
flying difficult and dangerous, so pilots usually avoid them.
References
Troposphere. (s/f). Nasa.gov. Recuperado el 6 de febrero de 2023, de https://spaceplace.nasa.gov/troposphere/sp/

Standard atmosphere. (2007). En Encyclopedic Dictionary of Polymers (pp. 921–921). Springer New York.

https://meteoglosario.aemet.es/es/termino/1007_altura-geopotencial

https://www.crocontrol.hr/en/services/aeronautical-meteorology/the-most-dangerous-weather-phenomena-in-aviation/#:~:text=Many%20other%20hazardous%20meteorological%20phenomena,gust%20fronts%20and%20funnel%20clouds.

FAA. (2008). Density Altitude. Recuperado de https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56396/FAA%20P-8740-02%20DensityAltitude%5Bhi-res%5D%20branded.pdf

Lewis, Cherry, Lawless et al. (1995). Introduction to Performance and Flying Qualities Flight Testing. Purdue University. Recuperado de https://engineering.purdue.edu/~andrisan/Courses/AAE490F_S2008/Buffer/Std_Atm_NTPS.pdf