Why do clouds in the distance appear to have flat bottoms and not when they get overhead?

Answer 1

The bottoms generally look flat because they ARE flat.

Clouds form when the cooling of the air due to expansion brings the temperature down to the dew point.  Unless the relative humidity varies a lot (and air is generally pretty well mixed), that's all going to occur at roughly the same altitude for the air in a given area.  Thus, the cloud bottoms are mostly flat.

When you look up at e.g. a cumulus cloud from below, you're seeing the puffy sides as well as the bottom and it stops looking so flat.

Answer 2

Here is the answer to a similar question sent to askascientist..com

Question - Why are clouds flat on the bottom?
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Dear June-

Before we look at why clouds are flat on the bottom, a little review on
how clouds form, or exactly what a cloud is, might be helpful.

Clouds are condensed water vapor in the atmosphere, either in a liquid, or
solid form. (Yes, some clouds are composed of tiny ice crystals, and these
are called "cirrus" clouds. They are very high in the atmosphere (above
20,000 feet), and they are the wispy, feathery-looking clouds in the sky.
Their bases are not flat, but may appear that way, because they are so high,
or far away from us.

The other kind of clouds, the ones composed from liquid water droplets, form
in a variety of ways, but the end result is air containing water vapor is
cooled to its saturation point, and then the water vapor condenses into
visible water droplets, called clouds. When air rises, it cools, and at a
particular level, it reaches its saturation point, and clouds form. That
level constitutes the bottom, or base of the cloud. (This level depends on a
variety of conditions, including temperature, air pressure, amount of
moisture in the air, etc.) But the height of the cloud bases over a given
area is fairly uniform, and the bases appear to be flat.

Answer 3

Most of the clouds that are overhead are not easy to be measured from the ground to the base of the clouds, but mostly in clouds that are near the ground will have the same base.
for example cumulonimbus usually have their base at 2000 or 2500, feet also cumulus and cumulus potentes will have the same base, while stratus, nimbostratus, alto stratus will always be high level clouds sometimes at 30 thousands feet..Clouds are related to different atmosphere phenomenons, such as cold fronts, hot fronts, stationary fronts and High and Low systems. Lack of clouds are usually find in High systems...I don't want to make it too difficult for you ..Weather analysis are great and wonder full . Hope I helped...good luck

Answer 4

Two out of the three types of clouds are generally flat. Stratus clouds are low clouds that form flat, wide layers. They usually mean snow or rain. It sounds like you are talking about cumulus clouds, though. They are usually dome shaped with flat bottoms. We see cumulus clouds on nice days. Since cumulus clouds are the ones that look like fluffy, white cotton, when they are over-head, they don't appear as flat. Its only when we see them at a distance when we notice their flat bottoms.

Answer 5

Perspective and point of reference.

Answer 6

it's a mirage.