As a long time weather observer in polar climes, and an aviation weather qa specialist, i would add that the etages are not a fixed thing, per say. They do compress (lower) towards the poles. For example, you may find what looks like stereotypical CI (cirrus) at 150 AGL at the poles, or AC Lenticularis (Altocumulus that is sheared almond shape usually by terrain and high resulting wind) at levels as low as 040 AGL, which technically makes them SC (Stratocumulus) (rotor clouds?). We would just put a remark in if it doesn't fit in the computer ;) There is only one resource that is authoritative in your country, and it is written within the directive provided by WMO. In Canada. we use this: https://www.ec.gc.ca/manobs/73BC3152-E142-4AEE-AC7D-CF30DAFF9F70/MANOBS_7E-A19_Eng_web.pdf this is the latest edition to date and legal in Canada, but may be a good guide for you also (I don't know what Country you reside in). Very clear cut etages were given in the past, but WMO has moved away from this as of MANOBS 18. The etages (the old term for heights) used to be extremely rigid. Now they are considered a guideline, acknowledging that the clouds and etages are both variable dynamic things, not something that can be set in stone (anymore). -And just to add, cloud heights are generally given as height above ground level (AGL), not ASL (above sea level) unless you happen to be observing them actually at sea level. Aircraft will report heights ASL, but the observer has to apply a correction (if report was given over the station) before publishing. I suppose there are some places where the height is below sea level, but I have no experience with this. Hope this helps!physea said:
Cory Buott said:
Cloud altitude refers to the height or vertical distance of a cloud from the Earth's surface. It is typically measured in feet or meters above sea level.
Cloud altitudes are determined through various methods such as satellite imagery, weather balloons, and aircraft observations. These methods measure the height of the base of a cloud relative to the Earth's surface.
The main factors that affect cloud altitude include air temperature, air pressure, and the amount of moisture in the air. These factors determine the height at which water vapor will condense and form clouds.
The range of cloud altitudes can vary greatly depending on the type of cloud and the atmospheric conditions. On average, clouds can form at altitudes ranging from 6,000 to 20,000 feet, but some high altitude clouds can reach up to 50,000 feet.
Understanding cloud altitude is crucial for weather forecasting and aviation safety. Different types of clouds form at different altitudes and can indicate changes in weather patterns. Additionally, pilots need to be aware of cloud altitudes to avoid flying through them and experiencing turbulence.
