In fact, you can have a very nice weather in a high pressure zone, with clear sunny sky and little wind, but during daytime, the pressure drops a little to climb up again during the night. That is a normal diurnal variation of pressure; when it is hot, air rises and pressure drops a bit. It is not the drop in itself but the rate of fall that is the most important point and that's why some people have barographs that register the pressure over time. An old seafarer's rule is that a pressure fall of ten millibars (today, called hecto-Pascal) in eight hours is a certain sign of a gale force wind coming in. And that is the only thing that is 100 percent certain in meteorology; a pressure fall must be followed by a wind of air trying to fill again the lower pressure.
Overview. 1  Babies can develop enlarged kidneys -- a condition known as hydronephrosis -- while still in the womb, or after birth. This condition is the most frequently discovered problem revealed by ultrasound examinations of babies in the womb.
But pregnancy isn't the only potential reason for an enlarged uterus. An enlarged uterus is common and can be a symptom of a variety of medical conditions, some of which require treatment. Two of the most common causes of an enlarged uterus are uterine fibroids and adenomyosis.