Cumulus Clouds in winter

[jerseydevil11]

This is related to the flat bottmed clouds post I read yesterday. I often observe those cumulus cloud formations in the middle of winter off the coast. Would there be a reason that these clouds form on very cold days? I thought that cumulus clouds were formed by convection on hot days.

[senorpepr]

This is related to the flat bottmed clouds post I read yesterday. I often observe those cumulus cloud formations in the middle of winter off the coast. Would there be a reason that these clouds form on very cold days? I thought that cumulus clouds were formed by convection on hot days.

Most likely the clouds aren't really "cumulus" as they are "stratocumulus" They are sort of a stable cloud, but they do have some of the characteristics of cumulus, such as individual elements unlike normal stratus.

Anyway, these clouds form primarily due to the warm surface ocean and nearby layer of air versus the colder air aloft.

Anytime you have cold air over warm air, you are in an instable situation. The cold air wants to sink and the warm air wants to raise. This helps to kick off the stratocumuli.

(I just have to throw this next part in...)

Remember, Cold Over Warm (COW) is instable. Cows are instable because of all the cow-tipping.

Warm Over Cold (WOC) is stable. You want the wok to remain stable so you don't spill your food.

(I know... it's sad... but it works.)

[wxmann_91]

This is related to the flat bottmed clouds post I read yesterday. I often observe those cumulus cloud formations in the middle of winter off the coast. Would there be a reason that these clouds form on very cold days? I thought that cumulus clouds were formed by convection on hot days.

Most likely the clouds aren't really "cumulus" as they are "stratocumulus" They are sort of a stable cloud, but they do have some of the characteristics of cumulus, such as individual elements unlike normal stratus.

Anyway, these clouds form primarily due to the warm surface ocean and nearby layer of air versus the colder air aloft.

Anytime you have cold air over warm air, you are in an instable situation. The cold air wants to sink and the warm air wants to raise. This helps to kick off the stratocumuli.

(I just have to throw this next part in...)

Remember, Cold Over Warm (COW) is instable. Cows are instable because of all the cow-tipping.

Warm Over Cold (WOC) is stable. You want the wok to remain stable so you don't spill your food.

(I know... it's sad... but it works.)

When you say "instable", don't you mean "unstable"?

Oh, and the last part's hilarious! Good mneumonic device.

[jerseydevil11]

Why are these formations perfect? All of the clouds are the same size. Do cumulus and stratocumulus always form to the same specifications?

[senorpepr]

When you say "instable", don't you mean "unstable"?

No... I mean instable.

instable

\In*sta"ble\, a. [L. instabilis: cf. F. instable. See In- not, and Stable, a., and cf. Unstable.] Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant.

[senorpepr]

Why are these formations perfect? All of the clouds are the same size. Do cumulus and stratocumulus always form to the same specifications?

The reason why the form to a given size is due to the atmosphereic conditions. The greater amount of moisture and amount of lift results in different sizes of cloud formations.

[jerseydevil11]

i am just interested as to why there are long lines of clouds instead of just a few very large clouds. There must individual convection cells in order to produce so many.

[Wthrman13]

i am just interested as to why there are long lines of clouds instead of just a few very large clouds. There must individual convection cells in order to produce so many.

Good question. What you are asking about is a phenomenon known as mesoscale cellular convection (MCC, not to be confused with the other MCC, mesoscale convective complex). This can occur in one of two ways: 1) heating of the surface, or 2) cooling of the top of the layer. In the case of stratocumulus-topped marine boundary layers, cooling due to radiation out to space is a primary cause of instability. For reasons that are still not fully understood, if you have a whole layer spread out over a large horizontal area that has similar characteristics, as is often the case over the cool ocean water in the winter, the convection cells that form as a response to this instability mentioned above spontaneously organize into lines which are oriented more-or-less along the direction of the mean wind in the boundary layer, or, if the winds are lighter, you can get cellular patterns of convection which take the form of hexagons, squares, or other polygons, with clouds at the centers or edges, depending on conditions.

[Wthrman13]

When you say "instable", don't you mean "unstable"?

No... I mean instable.

instable

\In*sta"ble\, a. [L. instabilis: cf. F. instable. See In- not, and Stable, a., and cf. Unstable.] Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant.

However, "unstable" is the most commonly-used term. Not to be nitpicky, but I've never heard of atmospheric conditions referred to as "instable", always "unstable". The condition of being unstable, of course, is "instability".

Sorry if I sound like an insufferable grammar Nazi!

[senorpepr]

When you say "instable", don't you mean "unstable"?

No... I mean instable.

instable

\In*sta"ble\, a. [L. instabilis: cf. F. instable. See In- not, and Stable, a., and cf. Unstable.] Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant.

However, "unstable" is the most commonly-used term. Not to be nitpicky, but I've never heard of atmospheric conditions referred to as "instable", always "unstable". The condition of being unstable, of course, is "instability".

Sorry if I sound like an insufferable grammar Nazi!

I know... I was being sarcastic with that last post.

[Wthrman13]

When you say "instable", don't you mean "unstable"?

No... I mean instable.

instable

\In*sta"ble\, a. [L. instabilis: cf. F. instable. See In- not, and Stable, a., and cf. Unstable.] Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant.

However, "unstable" is the most commonly-used term. Not to be nitpicky, but I've never heard of atmospheric conditions referred to as "instable", always "unstable". The condition of being unstable, of course, is "instability".

Sorry if I sound like an insufferable grammar Nazi!

I know... I was being sarcastic with that last post.

Ah, it all makes sense now

[Matt-hurricanewatcher]

A cumulus cloud is formed when the airmass is unstable. Which the air which is warmer then the air around it moves up. In cools intill its dew point, when the air parcel reachs its dew point it will form the "base" of your so called cloud. Now one of these don't form a cloud but millions even hundreds of millions. These Parcels stick on cloud nuci...

A cumulu cloud can be formed on a afternoon or by the lifting air infront of a cold front.

A stratus cloud forms when the airmass is stable. Which is most of the time in front of the warm front. This airmass has warmer air sliding up the the cool air in front of the warm front. Which adds lifted to form a soild area of thin clouds...

In between the two are like Senr side which are stratocu. Or other forms like that.

[wxmann_91]

There is another explanation - many time there are big extratropical/baroclinic systems in the winter. They bring down VERY COLD temperatures aloft. I'm not an expert in this but I do believe that even with temperatures at the sfc freezing, the frigid temperatures aloft will still allow fair-weather cumulus development.

[Matt-hurricanewatcher]

Wx_man91, its caused by the low pressure more then the cold air aloft. See cold air is heavier then warm air(In some ways)...Even so yes the Atmopshere cools as it get higher due to the less dense air=lower pressure. See a area of low pressure forces the airflow into the system=rising air. So if you got a system or ULL you can get clouds or maybe even Cumulus clouds.