Why there is no rain when clouds are scattered?

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Discussion Overview

The discussion revolves around the conditions under which rain occurs in relation to cloud density and moisture content. Participants explore the relationship between cloud formation, humidity, and precipitation, addressing both theoretical and observational aspects.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that rain primarily occurs from dense clouds, while scattered clouds do not produce rain effectively.
  • Others argue that rain can occur from scattered clouds, but it may evaporate before reaching the ground due to insufficient density.
  • One participant shares an observation of rain falling from a single dark cloud in otherwise clear skies, indicating that localized rain can happen regardless of overall cloud cover.
  • There is a discussion about the role of humidity, with some noting that high humidity can exist without clouds, suggesting that moisture concentration and temperature are critical for precipitation.
  • Participants clarify that clouds exist at 100% relative humidity or greater, which is a condition necessary for rain, but not solely dependent on cloud presence.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between cloud density and rain, with no consensus reached on the primary factors influencing precipitation. Some acknowledge that rain can occur from scattered clouds, while others emphasize the importance of cloud density.

Contextual Notes

Limitations in the discussion include varying definitions of cloud density and humidity, as well as the complexity of atmospheric conditions that influence precipitation. Observational experiences shared by participants may not universally apply.

Muthumanimaran
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Raining only occurs when there are dense clouds in the sky, when they are scattered the raining is stopped, why?
 
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In many clouds, it actually is raining. It's just that there isn't much rain falling and it evaporates before it gets to the ground. In a larger, denser cloud, the rain reaches the ground before it has a chance to evaporate.
 
Rain comes from clouds. Clouds are opaque because they contain condensed water dropplets.
 
This is not always true. When I lived in Houston Texas, there could be a medium sized single dark cloud pouring rain as it crossed over you, with otherwise clear skies. As the cloud was approaching or leaving, you could see a "wall" of water coming down from the leading or trailing edge of the cloud.
 
Maybe I misunderstood the question. If he was asking why rain is more likely on very cloudy days than moderately cloudy days, it is because a very cloudy day has more moisture in the sky. On a moderately cloudy day, a cloud has an easier opportunity to dissipate instead of raining.

But as per the above, certain weather patterns can cause rain from lone clouds, particularly pop-up thunderstorms.
 
russ_watters said:
Maybe I misunderstood the question. If he was asking why rain is more likely on very cloudy days than moderately cloudy days, it is because a very cloudy day has more moisture in the sky. On a moderately cloudy day, a cloud has an easier opportunity to dissipate instead of raining.

no, not necessarily ... you can have almost 100% humidity on a sunny summer day and not a cloud in sight. ie. the air/atmosphere is very moisture laden

its the concentration of moisture per unit of volume combined with temperature that will cause condensation and then precipitation
 
davenn said:
no, not necessarily ... you can have almost 100% humidity on a sunny summer day and not a cloud in sight. ie. the air/atmosphere is very moisture laden
A cloud is at 100% RH (or greater), which is greater than "almost 100%.
its the concentration of moisture per unit of volume combined with temperature that will cause condensation and then precipitation
Agreed.
 
russ_watters said:
A cloud is at 100% RH (or greater), which is greater than "almost 100%.

Agreed.

just pointing out that you can have 100% humidity on a couldless day
 

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