Why is it so hard to get an all day steady rain in the summer time?

Question

we always get thunderstorms that last anywhere from 5 min to 15 min, how come we dont see a steady all day in the summer time?

I live in Interior Southeast Va.

Answer 1

first, i don't know.

but sometimes i'm pretty good at guessing.

rain is fairly temperature sensative.

cool the air where the rain is condensing, and it rains harder.

warm it a bit, and it stops.

when water vapor condenses to a liquid, it gives up a considerable amount of heat, which heats the surrounding air.

looked at in that light, a better question to ask would be, why does it continue to rain in some cases?  what happens to all the heat released by the water vapor that condenses to liquid?

Answer 2

I will try to explain this simple as I can.  In order to get stratiform rainfall, which is steady rain in a large area, you must cool a large layer of air so that it will condense into a large and relatively thick area of clouds.  Then you must continue to cool it until the water droplets grow through the process of additional condensation and merging of droplets.

That much easier to do in the winter when you have a colder air mass.  And with a colder airmass, you would need only cool the atmosphere less degrees to reach the point where clouds will form and rain to occur in a large area when compared to a warmer summer airmass.

The best way to cool an airmass is by lifting the air upwards.  With a decrease in pressure as the air is lifted up, the temperatures  will cool as long as other variables stay constant.

In the winter, the cooler temperatures will result in a more stable enviroment.  With a more stable enviroment, you do not get as strong convective currents that are caused by strong daytime heating of the surface when compare to summer heating.  So showers are less likely to occur.  But in northern hemispheere, you do have a stronger difference of heating between the polar region and the tropics due to the tilt of the Earth on the axis.  This difference in heat energy will increase the activities of nature's attempt to try to put these differences into balance.  So nature will increase the scalr of transport the warmer air from the tropics to the north, and this will result in bringing colder air south.  When these areas of north bound warmer air moves north and meets the area of south bound colder air, what we get is the cold and denser air diving under the warmer air.  The cold air will cause a large scale lifting of the warm moist air and we will get the large area of stratisform rainfall or experience a steady period of rain.

In the warm season, the difference of heating between the poles and the tropics is less.  So we will see less intense large scale movement of air masses between the polar region and the tropics.  With the stronger heating, the convective currents will be stronger due to daytime heating.  And you will get the more extensive showers and thunderstorms as the result of pockets of air moving up and down next to each other.

It is the same situation as if you where to boil a pot of water.  You will see small air bubbles moving up as heat is transported upwards and not a massive one layer of air bubble moving to the top of the pot.

So in summary, in the warm season, convectional currents are the more likely precipitation producer than large scale lifting due to the warm and more unstable conditions.  In the winter, large scale lifting is more likely due to the stronger difference in solar energy between the poles and tropics.  With less surface heating, convection precipitation due to daytime heating are usually not as strong or widepread in the winter.

Hope this all make sense.