** Altitude vs Height
**

The altitude and height are two related terms often found in aerial navigation, geography, and many other subjects. Both are distance measurements in the vertical direction between two points, but the difference lies in the way they are defined and used.

Height is simply the vertical distance between two points. That is the vertical distance between two considered points.

Altitude can be defined in a broader sense as the vertical distance between a datum line and a point considered above that line. The datum line can be selected in many ways. Therefore, many altitude terms are in use. The basic forms of altitudes in common use are the indicated altitude and the absolute altitude.

**True altitude**: the height above the mean sea level. [Elevation of geographical locations given in maps is actually true altitudes; e.g. the height of the Mount Everest.]

**Absolute altitude:** absolute altitude is the height from the point on the ground just below the position considered. Or it is the height above the ground level.

**Indicated Altitude:** altitude from the altimeter, when it is set for the local barometric pressure at the mean sea level. [aircrafts use outside pressure to determine the altitude of the aircraft.]

**Pressure Altitude:** Pressure altitude is the height above a standard datum air-pressure plane. When the altimeter is set with 1 ATM or 1.0132×10^{5} Pa as the local barometric pressure at the MSL, indicated altitude and the pressure altitude are the same.

**Density altitude:** Density altitude is defined as pressure altitude corrected for variations from standard temperature. Based on the parameters such as temperature, the pressure at a point can vary from the International Standard Atmosphere. Since all the flight characteristics are in Standard Atmosphere conditions, it is important to know at which altitude in the international standard atmosphere this particular pressure is observed. That altitude is the density altitude.

Also based on physical properties in each region, atmosphere is divided into several altitude regions. They are as follows;

*Troposphere : 0 m -8000 m (0-80 km)*

*Stratosphere : 8000 m -50000 m (8-50km)*

*Mesosphere : 50000m- 85000 m (50-85 km)*

*Thermosphere : 85000 m – 675000 m (85-675 km)*

*Exosphere :67500 m – ~10000000 m (675-10000 km) *

**What is the difference between Altitude and Height?**

• Height is the distance between two points in the vertical direction.

• Geometric altitude is a height from a datum line to a point above that line.

• In practical applications, in aviation, the height is obtained by comparing the outside atmospheric pressure to the International Standard Atmosphere.

• The main difference between height and a geometric altitude is that altitude has a defined / fixed datum point as a reference.

• Pressure altitude and its derivatives are not comparable to height.