Blog #3

On a mesoscale level, the Continental Polar air mass affects Ann Arbor during the winter. This air mass is cold and dry due to its origins over inland Cananda. The city is also affected by the maritime tropical air mass during the summer, bringing warm, humid air to the north. Michigan is unique because it is a region with large water bodies in the middle of a continental mass, resulting in climate characteristics that are specific to the region.

On a microscale level, as the cold Continental Polar air mass reaches the Great Lakes, the Lake Effect is created due to cold air over warmer water. As the cold air and warm water meet, water evaporates into the air and is carried southwest toward the continental United States. When this humid air mass reaches orographic barrierrs, particularly mountains, Michigan experiences heavy snow or rain.

Although Ann Arbor is near a body of water and the temperature would seem to be fairly stable, the winter months and summer months have noticeable contrast. Ann Arbor is close enough to the Great Lakes to experience the Lake Effect in the winter months, but is too far inland to be cooled by the breeze from the Great Lakes during the summertime, causing differentiation between winter and summer seasonal temperatures. However, Ann Arbor remains humid throughout the year and experiences thunderstorms in the summer, causing the growth of lush greenery.

In comparison with Puerto Limon, Costa Rica, Ann Arbor, Michigan has some interesting similarities and differences. Puerto Limon experiences high sunlight intensity due to its location near the equator, steady rainfall, and steady temperatures due to its coastal location. Ann Arbor also has somewhat steady precipitation, it tends to be more concentrated during the winter months, as well as temperature fluctuations between seasons. While Puerto Limon is affected exclusively by the maritime tropical air mass, Ann Arbor is affected by several air masses including the continental polar, continental tropical, and maritime polar air masses depending on wind patterns.

Blog #2: Ann Arbor

The air mass that mainly affects Ann Arbor, Michigan is the continental polar air mass during the winter, which stretches from northwestern Canada through Michigan. This air mass is cold and dry due to its origins over inland Cananda and southern movement towards the continental United States.

Ann Arbor is also affected by the maritime tropical air mass during the summer, bringing warm, humid air to the area.

Relative humidity in the area is above average, ranging from around 40%, which is considered comfortable, to near 100%

Relative humidity highs and lows throughout the year in Ann Arbor, Michigan:

Ann Arbor, Michigan does experience some mid-latitude cyclone activity. Mid-latitude cyclones are the result of baroclinic conditions. Because there is an energy and temperature imbalance between earth's poles and equator, pressure surfaces cross one another in the atmosphere and isobars and isotherms cross paths as opposed to barotropic conditions, where the isobars and isotherms are parallel. Winds caused by the westerlies create divergence and convergence, resulting in areas of both high and low pressure at Earth's surface.

A few years ago, Ann Arbor was affected by a mid-latitude cyclone for the duration of several days:
https://www.youtube.com/watch?v=n4rJX4IIRaU


These mid-latitude cyclones are the result of a cold front from the north (continental polar) and a warm front from the south (maritime tropical). Maps for the upcoming days show a warm and cold front moving over Michigan, but no cyclonic activity is likely to occur. Map for April 15, 2014:

 Map for April 17, 2014:

Light showers are expected for Friday the 18th, but the weekend is likely to be in the 50s and no cyclonic activity is predicted.

There is one local phenomena that influences the weather in Ann Arbor and throughout the eastern portion of the state. Because Michigan is surrounded on three sides by the Great Lakes, proximity to water has some consequences for the area. For example, cool air from Canada moving across the Great Lakes will cause water to evaporate if the Great Lakes are warm enough. Depending on wind speed and direction, the moist air may reach higher elevations over land. Once over cool land, moist, unstable air is forced to ascend, either causing or enhancing precipitation. This is referred to as the "Lake Effect."


 Lake Effect snow storm video and animations:

http://www.bing.com/videos/watch/video/lake-effect-snow-guns/8lmyn5a1


Resources:

http://www.srh.noaa.gov/jetstream/synoptic/airmass.htm

http://www.cmmap.org/scienceEd/summercourse/summerCourse11/docs/KateThursdayPM.pdf

https://www.youtube.com/watch?v=n4rJX4IIRaU

http://www.accuweather.com/en/us/national/weather-surface-maps

http://www.mlive.com/news/index.ssf/2011/09/cyclone_sticks_on_michigan_see.html

http://weatherspark.com/averages/29652/Ann-Arbor-Michigan-United-States

Ann Arbor, Michigan Weather and Climate

Ann Arbor, Michigan is a located southwest of Detroit on the Huron River in an agriculturally productive area. The elevation ranges from 750 feet-1,000 feet. Parts of the city are densely forested and surrounded by grasslands and croplands. The estimated Bowen Ratio for Ann Arbor would be around .6 due to the humid continental climate and physical geography.

Ann Arbor experiences consistent atmospheric stability with cold winters and warm summers. Average summer highs reach the mid-80s in late July and average winter lows are in the teens around mid-January. Consistent with most of the northeast, Michigan has prominent seasons. The warm season lasts from May through September with an average high daily temperature above 72°F, while the cold season occurs from November through March with an average high daily temperature below 40°F.

Temperature averages in Ann Arbor over the last thirty years:

Cloud cover is consistent with the seasons; the more clear time of the year begins on March 20^th while the cloudier part of the year begins in late October. 

Cloud cover in Ann Arbor over the last ten years:

Because Michigan is surrounded on three sides by the Great Lakes, proximity to water has some consequences for the area. For example, cool air from Canada moving across the Great Lakes will cause water to evaporate. The vapor then cools and condenses into clouds. Once over cool land, clouds will produce snow on the shore or inland. This is referred to as the "Lake Effect."

 Interesting animation of the Lake Effect:

http://svs.gsfc.nasa.gov/vis/a000000/a001200/a001271/a001271.mpg

Wind can influence weather patterns in the Ann Arbor area, especially in terms of the Lake Effect. The city experiences wind speeds from 0 to 16 mph (calm to moderate breeze). For the most part, wind blows in the south or southwest direction, bringing weather to the city from over Lake Erie and sometimes Lake Huron.

Wind directions in Ann Arbor over the last ten years:

Precipitation is somewhat predictable; the highest probability of snow occurs during the cold season and the highest probability of thunderstorms occurs during the warm season.

Probability and types of precipitation in Ann Arbor over the last ten years:

 Overall, light snow is the most common form of precipitation. Although cloud coverage lessens during the summer months, the warm season experiences the most precipitation with around 3.5 inches per month from thunderstorms, while the cold season receives between 2.5 and 3 inches per month from light snow. There is no dry season for the city. Over the last 30 years, the mean annual total precipitation was 37.4 inches.  Snowfall during the winter ranges from moderate to heavy. The highest amounts of snowfall occur during December through February.

Common precipitation types in Ann Arbor over the last ten years:

Overall average amount of precipitation in Ann Arbor over the last thirty years:

Ann Arbor is located in the cP air mass, or continental polar air mass. This air mass is cold and dry due to its origins over inland Cananda. However, Ann Arbor is a fairly humid area due to its proximity to the Great Lakes. There is some potential for severe weather for the city. Tornado activity is significantly above average compared the rest of the state of Michigan, and well above average compared the United States. Earthquake potential is also slightly above average in comparison to the rest of the state and United States.

 Michigan State Theater in Ann Arbor during a snow storm:

Resources:

http://www.ncdc.noaa.gov/cag/

http://www.ncdc.noaa.gov/oa/climate/normals/usnormals.html 

http://svs.gsfc.nasa.gov/vis/a000000/a001200/a001271/a001271.mpg

http://weatherspark.com/averages/29652/Ann-Arbor-Michigan-United-States

http://glisa.umich.edu/docs/AnnArborMI_Climatology.pdf

 http://www.weather.com/weather/wxclimatology/monthly/graph/48109

http://www.x98ruhf.net/lake_effect.htm

http://weatherspark.com/averages/29652/Ann-Arbor-Michigan-United-States

http://markbialek.com/ann-arbor-nights-snowstorm-shoot/