Cloud
Table of Contents
Terms:
- Stratus means layered - Flat clouds
- Cumulus means fluffy
- Cirrus means thin, hair like
Clouds:
- Stratocumuls: Fluffy clouds that are flat (i.e. stratiform + cumuliform).
- Cumulus: Fluffy popcorn like clouds. They are not flat.
- Startus: Flat grey colored clouds. They are not fluffy.
- Cirrus: Thin hair like at very high altitude. Made up of ice crystals not water droplets.
1. Cloud deck
One day I saw from an airplane window clouds at same elevation. I searched for an explanation and this is my note.
Figure 1: A picture of clouds taken on 2026-01-11 on a flight from Chicago to Atlanta.
When you see a layer of flat clouds (called a cloud deck) it is formed in following way:
- Moist air rise, and reaches it lifting condensation level, forming clouds
- Temperature inversion prevents it from rising further and they spread out horizontally.
Key phenomenon:
Temperature inversion: As altitude increases temperature decreases. But sometimes, the temperature can increase after a altitude. This can happen because of:
- Radiation
- Frontal: When warm air collides with cool air, it glides over the cool air
- Advection: When warm air blows over cold ground (e.g. snow, water body), the lower portion of the warm air cools down
- Subsidence inversion: Air subsides (sinks) from high to low, and gets compressed due to pressure causing adiabatic heating.
- Topographic: Air from mountains flows down to the valley causing lower air to be cold, while upper reamins warm
For temperature inversion we also need light winds so that the air is not disturbed much.
- Lifting Condensation Level: The altitude at with a rising air with mositure cools to it's dew point cause invisible water vapour to turn to visible water droplets.