So far we have dealt with clouds whose dimensions extended mainly in horizontal extension but this time we address the vertically developing clouds and we are going to start with one of the two genres that can be classified like this, we are talking about the Cumulus.
On Cumulus They are isolated clouds, generally dense and with well-defined contours, which develop vertically in the form of bumps, domes, or towers, and whose convex tops often resemble a cauliflower. The sunlit parts of these clouds are bright white; its base is dark and horizontal. Sometimes they appear torn by the wind.
These clouds are mainly made up of water droplets or by ice crystals in those parts of the cloud that, due to their altitude, are at temperatures below 0º C. In addition, they may contain supercooled water droplets. Cumulus They develop when they occur convective currents caused by the uneven heating of the air above the Earth's surface. This rising air condenses into a cloud and grows depending on the degree of instability of the air at that time. If you're interested in learning more about how clouds form, you can read about the formation of clouds.
On Cumulus In good weather, they typically grow in summer from midday until sunset, when they dissipate. However, if there is a certain degree of instability, they can progress to Cumulus congestus and, if applicable, become cumulonimbus, which are clouds associated with showers and thunderstorms. They should not be confused with the Stratocumulus, nor with the cumulonimbus.
Clouds Cumulus They contrast perfectly with the blue sky due to their high density, which makes them appear white and bright. For the same reason, their bases appear dark or black. For maximum contrast between cloud and sky, it is recommended to use the polarizing filter and adjust the focus to the protuberances. In this regard, to better understand how clouds differ according to their altitude, it is interesting to consult the article on height and altitude of clouds.
They are distinguished four species of cumulus clouds:
- cumulus humilis (low development)
- Cumulus mediocris (moderate development)
- cumulus congestus (piled, with accentuated vertical development)
- Cumulus fractus (torn or fragmented clouds)
In addition, there is a variety known as Cumulus radiatus which is presented in horizontally arranged rows or alignments. The characteristics of each species of Cumulus They depend fundamentally on their vertical extension, that is, the vertical distance between their base and the stable layer that has inhibited vertical development.
When the degree of stability and the thickness of the stable layer are significant, this can inhibit the vertical development of clouds. If there is a strong thermal inversion, the tops of the clouds Cumulus will spread out and form a Stratocumulus cumulogenitus or Altocumulus cumulogenitus. On the other hand, if the layer is stable but not very thick, some cloud tops Cumulus They can expand only in certain parts or momentarily, allowing some peaks to pass through it.
Observations on the vertical extent of clouds Cumulus:
- When a Cumulus has a large vertical extension (a low base and a high stable layer), it is of the species congestus; the vertical extent of Cumulus clouds in tropical regions (if not under the influence of a trade wind inversion) is usually much greater than in other places.
- When a Cumulus shows a moderate vertical extent (the base and the stable layer are reasonably close), the tops of the Cumulus mediocris can expand, giving rise to a Stratocumulus or altocumulus.
- Clouds with little vertical extent (the base and stable layer are very close together) have a flattened appearance and are designated as cumulus humilis; they can even extend completely and transform into a Stratocumulus o altocumulus.
- On Cumulus They can dissipate during the day as the surface air temperature increases and their bases rise until their height significantly exceeds the height of the stable layer. For more information on how clouds dissipate, see at this link.
- When there is no vertical extension (the stable layer is below the level where there is enough cooling to generate condensation), there may be Cumulus Only if there is a mechanism that forces the air to rise to the level where condensation is possible; orographic ascent is a good example of this type of mechanism.
Diurnal variation in activity Cumulus It is generally pronounced on land. On clear mornings, when the sun quickly warms the Earth's surface, conditions are favorable for the formation of CumulusThis formation can begin early when the vertical gradient is intense and the relative humidity is high; however, when the vertical gradient is small, the Cumulus, if they form at all, they do so late. Once a maximum is reached, usually in the mid-afternoon, the activity of the Cumulus decreases and finally the clouds disappear in the late afternoon or early evening.
At sea, the activity of the Cumulus It is rare, and sometimes even doubtful of its existence. When they do appear, they seem to be most active late at night. On the continent, Cumulus They form during the day in combination with the sea breeze, while on the ocean, this occurs at night in combination with the land breeze, especially near the coast.
The lighting characteristics of the Cumulus well developed are notable:
- When the Cumulus Observed against the sun, the diffuse reflection of sunlight falling on its surface reveals its relief thanks to marked differences in luminance.
- When the Cumulus It is lit from the side, showing shadows with intense contrasts that emphasize its shape.
- When the Cumulus It is backlit, looks relatively dark, with an extremely bright edge.
- When the Cumulus It is located on a background of cirriform clouds and far from the horizon, it is observed to be somewhat less white than the cirriform clouds, and its margins tend to be grey, even in direct sunlight.
Regardless of the lighting of the Cumulus, its base is normally grey. A Cumulus can develop due to the convection which is caused by heat emitted by forest and wildfires or volcanic eruptions. In this case, it would be classified according to its species, variety, and corresponding supplementary traits, followed by "flammagenitus" (e.g., Cumulus congestus flammagenitus).
Also, a Cumulus It can form as a result of human activity, for example, convection over the cooling towers of a power plant. If the formation of a Cumulus It is due to human activity, it is classified according to its species, variety and corresponding supplementary traits, followed by "homogenitus" (for example, Cumulus mediocris homogenitus).
Finally, a Cumulus It can develop locally in the vicinity of large waterfalls due to the spray generated by the fall. It would be classified according to its species, variety, and corresponding supplementary traits, followed by "cataractagenitus" (e.g., Cumulus mediocris cataractagenitus).
Understanding Clouds Cumulus and their development is not only aesthetically fascinating, but is also essential for meteorology and weather forecasting. To learn more about other types of clouds, such as Cumulonimbus cloudsObserving these cloudy phenomena allows meteorologists and weather enthusiasts to predict changes in the climate and better understand the atmospheric patterns that affect our planet.
