Explanation of altitude nominations

[NorJesus]

I am searching for a clear diagram or explanation of what the altitude nominations in the Windy app represent in meters or feet.

For example, when looking at the cloud forecast:

• 300h = 9 km = FL300
• 500h = 5 km = FL180
• 700h = 3 km = FL100
• 800h = 2 km = 6400 ft
• 900h = 900 m = 3000 ft

What are the different altitude systems?

[idefix37]

@NorJesus

• 900h means 900hPa. It is expressed as a pressure level.

• 900m is the altitude (elevation) above mean sea level expressed in meters. It corresponds the 900hPa mean pressure level.

• 3000ft is a flight level expressed in feet (or in units of 100ft when displayed as FLxxx). It corresponds the 900hPa mean pressure level.