Convective Cumulus and Cumulonimbus
Cumulus clouds are mid-level based clouds that tend to bubble up and cover the sky like balls of cotton. They tend to form out of an otherwise clear sky due to convection. They can remain as fair-weather cumulus, or they can continue to develop in height and become cumulonimbus clouds where they produce precipitation and at times lightning. While the right synoptic set up can cause them to form over any of the skies in the area, Marys Peak, and any of the surrounding mountains, can help enhance their development. Air temperature decreases with height in the atmosphere because of the lower pressure. However, the ground is the primary source of heating the air. With surface heating occurring, the air along the slopes of Marys Peak will often be warmer and more humid (from evapotranspiration from the vegetation) than the surrounding free atmosphere. This warm air along the slopes is more buoyant than the surrounding cooler air and begins to rise like an air bubble in water. At the same time, rising air cools, which allows the relative humidity to increase. If the relative humidity reaches 100%, where the temperature and the dew point are equal, a cumulus cloud will form (in other words, it has reached the LCL). The base of convective cumulus is often above Marys Peak. However in the late mornings, during the cooler months, or between rain showers, the base of cumulus can cover and obscure the top of Marys Peak, as the LCL may be lower. For more information on general cumulus clouds, click here.
Our MissionThis webcam was funded by the National Science Foundation, with the original camera being installed by the Ocean Mixing Group on the roof of Burt Hall at Oregon State University on April 28th, 2010. The webcam is a part of experimental investigations into the physics of form drag in geophysical flows. The Biomicrometrology Group maintains the site as part of ongoing studies to understand and quantify interactions between the air, vegetation, and the land surface. The images obtained here are intended to complement studies of controlled flows over topographic obstacles in ocean and atmosphere. On August 4th, 2014, the Biomicrometeorology group at Oregon State University installed a new camera with near-infrared sensitivity to increase the window of viewability.
A collaborative, NSF-funded project by
C. Thomas, S. deSzoeke, L. Mahrt & E. Skyllingstad / OSU Atmospheric Sciences
J. Moum & J. Nash / OSU Ocean Mixing Group
Cloud Atlas compiled by REU student M. Spagnolo