Blog Post #3

The close proximity to the Alps Mountain range is the biggest determining factor for the meso and micro scale climate in Zurich.  There is a high level of orographically determined precipitation and temperature.  Zurich is in a valley north of the Alps and the meso scale climate varies greatly from year to year but is typically the opposite of what the Southern Alpine Region is experiencing.  The air masses that move over the region determine which side of the mountains receive the precipitation.  If Zurich is rainy there is a high probability that the Southern Alps will be dry, and vice versa.  Several programs have been implemented to try to study the patterns of meso scale climate in Switzerland, the RAPHAEL program and the Mesoscale Alpine Programme are two examples.  Their aim was to be able to predict precipitation for the mitigation of flood risk.  They found incredibly varying levels of rain and snowfall, the variability, again, is orographic in nature.  They were able to attain accurate predictions of location of rainfall but the amounts proved impossible to predict.

In the winter Zurich has less precipitation because the air masses are largely from the south which means they drop their moisture in the south before flowing over the Alps.  In the summer the effect is the opposite as air masses are coming down from the north and dropping rain over the region.  As the air masses in the region shift the wind speeds and directions also shift, when they are moving east to west there can be devastating effects in the region.  The valley Zurich lies in is generally oriented east to west.  Therefore when air masses are moving this direction they pick up speed while moving along the mountain range.  Extreme wind events are very common.

Fig. 1: Wind gusts as a function of return period in Zurich-Fluntern. The blue curve represents the function calculated by means of statistical analysis. Wind gusts measured over the period 1981-2007 are depicted by black dots. See text for further details. Source: http://www.meteoschweiz.ch/web/en/climate/climate_reports/frequency_of_extreme_wind_speeds.html

On a micro scale the same forces are at work.  Zurich is also a large city, with a population of slightly over 1 million living in an area of 38.5 square miles.  There is most certainly an urban heat island effect happening on a micro, local level.  The main weather station that collects data for Zurich is located at the airport.  Airports are large plots of concrete which reflect a lot of heat.  This weather station is naturally going to reflect higher temperatures than a station located on top of a mountain nearby.

Historical data has been collected in Switzerland 1870, this data is currently being used to forecast impacts and determine the severity of climate change in the region.

Source: http://www.meteoschweiz.ch/web/de/forschung/publikationen/alle_publikationen/Das_Schweizer_Klima_im_Trend.html

 This graph shows the average winter temps recorded in Zurich from 1870-2000.  There is a clear upward trend indicating that temperatures have been steadily rising in the area.  This does not necessarily mean that climate change is the cause.  As mentioned earlier this is a highly urbanized area and some of this warming could be a result of an urban heat island effect.

Source: http://www.meteoschweiz.ch/web/de/forschung/publikationen/alle_publikationen/Das_Schweizer_Klima_im_Trend.html

This graph shows the average summer temperatures from 1870-2000.  The trend lines in this graph are far less impressive than the rise in temperatures for winter months further suggesting that climate change is probably not the only factor in changing temperatures.

Source: http://www.meteoschweiz.ch/web/de/forschung/publikationen/alle_publikationen/Das_Schweizer_Klima_im_Trend.html

This precipitation graph also shows very little historical change, there is a slight noticeable increase over the last 130 years but it is minimal and probably has more to do with reflection of anomalies over time.

Source: http://www.wunderground.com/history/airport/LSZH/1997/1/30/MonthlyHistory.html?req_city=NA&req_state=NA&req_statename=NA

This graph is based on temperatures recorded at the weather station in Zurich from 1996-2012, with the obvious exception of June 2012.  As in the graph above depicting historic summer temperatures there does not seem to be a clear indication of consistently rising temperatures.  Although 2003 was an incredibly unusually warm winter.

The Koppen-Geiger classification system was put in place by two Germans, it was created in 1928 and placed broad classifications on the continents based on observed climate patterns.  Switzerland is in an area that has a lot of diversity topographically and was clearly difficult to classify.

Source: http://en.wikipedia.org/wiki/File:Koppen_World_Map.png

Europe according to Koppen-Geiger

 This is obviously not an exact science and these borders cannot be clearly defined.  As this picture indicates Switzerland is full of flux climatically.  According to this graphic most of Switzerland lies in what Koppen-Geiger classify as tundra.  This means that there is at least one month of the year warm enough to melt snow but no full month with an average over 50F.  This has huge impact on the types of vegetation and wildlife that can exist in the area.  Tundra, or Alpine, environments perfectly fit the Swiss environment.

Source: http://www.bing.com/images/search?q=climograph+of+zurich&view=detail&id=FCD9125C92E11CA9E34E5EECA27B625EF0D3546F&first=0

Reflection Post: Zurich, Switzerland vs. Lima, Peru

Lima Coastline hugs the Pacific Ocean

Source: http://www.worldatlas.com/webimage/countrys/samerica/pe.htm

The other location I was interested in researching for this blog assignment was Lima, Peru.  So, instead of doing the research myself I will compare the work of another student to my chosen location in Switzerland.  These two areas are very different in terms of climate.  They are nearly opposite in terms of meritimity and continentality, they are in different hemispheres which makes summer and winter months reversed and they are latitudinally very different as well.  The only thing Lima and Zurich have in relative common is that they are both located near a mountain range.  Even this topographical similarity does not provide a lot of commonalities between the two.  Lima is situated near the coast of the Pacific Ocean receiving foggy air before it hits the Andes Mountains.  Zurich is in a valley doesn't receive oceanic or sea air until after it flows over the Alps.  This makes the effects of the mountains on the air masses opposite in these two cities.  When Zurich is experiencing more northerly air masses it sees the same foggy conditions as Lima, but these air masses are colder as they have come from polar regions in Russia and Northern Europe. 

Zurich is located much further away from the equator than Lima and therefore has much more drastic weather patterns.  It gets much colder in the winter and sees much more precipitation, especially in the form of snow.  This also means that Zurich experiences mid-latitude cyclonic conditions whereas Lima experiences effects from the ICTZ.  The West Coast of South America is also greatly affected by El Nino and La Nina, Pacific Ocean patterns that are extremely different than the forces acting on Switzerland. 

Landlocked Zurich is surrounded with mountains, lakes and rivers

Topographical Phenomena of Zurich, Cyclones, and Air Masses

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

Four advective wind situations are defined for Switzerland, they are horizontal air flows, a low pressure, cold system from Iceland and a high pressure system from the Azores.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

During Northfoehn the precipitation in Zurich increases as air moves toward the Alps in the south.  The rise and cool as they approach the Alps creating clouds.

During Southfoehn conditions the precipitation is much greater because the air is moving in from the Mediterranean Sea.  Zurich is on the leeward side of the Alps during these condition so it will often see a foehn window where the cloud breaks up.

During a Bise situation the air is moving easterly, Zurich is on the eastern side of the country and therefore sees less wind than the west side where the mountain ranges get closer and the valley gets narrower.

West Winds blow for approximately 60% of the year, and creates more intense weather on the north side of the Alps than the south.  This is an important factor for the local weather conditions.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

 This is a westerly polar front connecting two low pressure cells.  The polar front is forcing it's way under the warm front from the east and causing a cold occlusion.

Two convective systems are defined for Switzerland, the anticyclone and the flat pressure distribution system.  These convective air movements create local climate conditions by vertically moving air.  Differences in local high or low pressure conditions will cause differing local winds.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

Anticyclonic patterns create fairly boring weather patterns.  The air is dropping slowly while losing humidity.  They do tend to create haze or stratoform clouds, especially in winter in low lying areas north of the Alps.

Flat Pressure distribution results in rising air, converse to anticyclonic patterns, they are more likely to form cumuloform clouds.

The Swiss Alps have a lot of influence on the weather and climate of the country, when precipitation is compared to different regions such as Oklahoma where the land is flat the patterns are very different.  Because systems get interrupted and don't have time to build up they tend to be more mild.  Switzerland does see hail storms but they do not see intense tornado producing thunderstorms like Oklahoma does.

The air masses that occur over Zurich are much the same as the rest of Europe.  The continent itself is relatively small, mostly falls in high latitudes and is largely surrounded by water. 

In the summer months Continental Polar (cP) and Maritime Polar (mP) air masses dominate.  The cP air masses are cooler whereas the mP masses are more stable in temperature, having crossed the Atlantic Ocean.  When these two air masses meet they develop cyclonic summer precipitation.  Summer months also see influence Continental Tropical (cT) and Maritime Tropical (mT) air masses.  These tropical air masses have some influence but because they are blocked by mountains and stabilized by ocean and sea they produce far less dramatic weather events than similar air masses in North America.

In winter months the same four air masses are influential.  The mP and cP fronts are what cause most of the precipitation in the Alps however it falls mostly to the south and affects Zurich less.  The clashing of mT and cT air masses have similar effects.

Source: http://www.publishyourarticles.org/knowledge-hub/articles/brief-notes-on-air-masses-of-europe.html



Source: http://www.wunderground.com/global/stations/06670.html

This is a satellite image of Swizterland from April 5, 2012.  The current temperature at 9:10pm CEST was 47F and raining.  The data is collected from the Zurich Airport and is accompanied by webcam photos.  Tomorrow's forecast says 0% chance of precipitation and a high of 57F with fog.

Here is a link to view, among many things, a live webcam of the Zurich airport. Live Web Cam at Zurich Airport

Source: http://www.zurich-airport.com/desktopdefault.aspx/tabid-277/473_read-113/