chapter6–clouddevelopmentandforms.ppt

Chapter 6 – Cloud Development and Forms Cloud Formation Condensation (i.e. clouds,fog) results from: Cloud Formation Condensation (i.e. clouds,fog) results from: Diabatic cooling (important for fog) Cloud Formation Condensation (i.e. clouds,fog) results from: Diabatic cooling (important for fog) Adiabatic cooling (important for clouds) Cloud Formation Condensation (i.e. clouds,fog) results from: Diabatic cooling (important for fog) Adiabatic cooling (important for clouds) Clouds form due to adiabatic cooling in rising air Γd = 9.8oC/km (unsaturated lapse rate) Γm ~ 5oC/km (saturated lapse rate) How Does Air Rise? 4 mechanisms cause air to rise: 1) Orographic lift – air that rises because it is going over a mountain How Does Air Rise? 4 mechanisms cause air to rise: 1) Orographic lift – air that rises because it is going over a mountain 2) Frontal lift – air that rises at a front How Does Air Rise? 4 mechanisms cause air to rise: 1) Orographic lift – air that rises because it is going over a mountain 2) Frontal lift – air that rises at a front 3) Horizontal convergence – air that is forced to rise because it is converging How Does Air Rise? 4 mechanisms cause air to rise: 1) Orographic lift – air that rises because it is going over a mountain 2) Frontal lift – air that rises at a front 3) Horizontal convergence – air that is forced to rise because it is converging 4) Convection – air that rises because it is less dense that its surroundings Orographic Lift Air rises as it approaches a mountain peak Orographic Lift Air rises as it approaches a mountain peak Orographic Lift Air descends after it goes over a mountain peak Rain Shadow A rain shadow is an area of less precipitation and clouds on the downwind side of a mountain (the anti-cloud!) Rain Shadow A rain shadow is an area of less precipitation and clouds on the downwind side of a mountain (the anti-cloud!) A