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.
Clinical Information. 1  Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine from draining into the bladder. 2  Abnormal enlargement or swelling of a kidney due to dilation of the kidney calices and the kidney pelvis.