Over the past few days the #weather has been settled owing to there being a #HighPressure region over us. The #pressure is now dropping and air from other parts of the world will start to rush in and inevitably, different air masses, at varying temperatures and humidities will mix. This sets up perturbations in the #atmosphere and steady #TemperatureGradients get perturbed and so, instead of having #clouds with flat undersides, they start to show undulations (spatial oscillations). Cont...