Orographic Lifting, Unstable Air, and Clouds in Estes Park

     The landscape of Estes Park is beautiful and interesting, but so are the cloud formations. We can often see multiple types of cloud formations. Fog also occurs often in Estes Park. Orographic Lifting and unstable air helps to create the fog and cloud formations. Let's look at how clouds and fog in Estes Park can be formed.

     Upslope fog is a common occurrence in Estes Park. Upslope fog is caused by orographic lifting. Barriers, such as the mountains in Estes Park, block horizontal air movements causing the air to move up the slope of the mountain. As the air travels upslope, it is cooled to the dew point and the water vapor condenses. The dew point is the temperature at which air becomes saturated. The orographic lifting can cause air to become unstable so the air could keep rising vertically. If the air remains stable, it could go down the other side of the mountain. 

The mountains blocked the horizontal air causing the air to move up the mountains. The water vapor condensed and became fog. Photo by me, Sylvia Jackson.

Orographic lifting caused the air to become unstable. Instead of going down the mountains, the air kept rising passed the lifting condensation level, creating the fluffy cumulus clouds. Photo by me, Sylvia Jackson.

     Clouds are created when water is condensed into very small droplets of liquid or ice. Clouds are classified by height and structure. Some of the clouds we see in Estes Park can be formed due to unstable air and orographic lifting. Air is unstable when a mass of air is warmer than the air around it. The warm air mass will rise until it reaches surrounding air that is a similar temperature and density. If the air reaches the lifting condensation level, clouds can form.

High level clouds are cirro-form clouds which look wispy. Mid level clouds are given the prefix alto. Cumulus-type clouds develop vertically and are lumpy. Stratus means that the clouds are layered and featureless. Nimbus means that the clouds are low and gray. Source: http://www.srh.noaa.gov/jetstream/clouds/types.htm

 These wispy looking clouds are cirrostratus. Photo by me, Sylvia Jackson.

These layered clouds are nimbostratus. Photo by me, Sylvia Jackson.

The fluffy clouds are altocumulus and the featureless gray clouds underneath are stratus. Photo by me, Sylvia Jackson.

These fluffy clouds are cumulus clouds. We can see the lifting condensation level in this image because the clouds have flat bases. Photo by me, Sylvia Jackson.

     Orographic lifting can cause air to become unstable. Orographic lifting occurs when a barrier blocks horizontal air movement. Air is unstable when it rises vertically with no external force. Orographic lifting and unstable air can make water vapor become condensed and create clouds and fog. Clouds are classified by their height and structure.

Sources:

Dr. Casey Allen's lecture “Weather & Storms”

Dr. Casey Allen's lecture “Water, Moisture, and Clouds”

McKnight's Physical Geography: A Landscape Appreciation, Edition Eleven by Darrel Hess

http://www.earthonlinemedia.com/ebooks/tpe_3e/atmospheric_moisture/clouds_1.html

http://www.srh.noaa.gov/jetstream/clouds/types.htm