Whilst many people take for granted the visual beauty and expanse of Lake Michigan, its colder temperatures in comparison with many other Great Lakes are worth noting. The fourth largest of the five Great Lakes, it spans four states—Michigan, Illinois, Wisconsin and Indiana—providing an ‘inland sea’ to a vast region on the north-central part of the continent.
It is known as having the greatest depth amongst the Great Lakes, with a maximum depth of 923 feet. This perhaps explains why its water remains on average 5° to 6° degrees colder than its four larger neighbours, including Lake Ontario and Lake Superior.
Whilst it remains unclear why the bottom depths are cooler than the surface waters, Dr. Brian Eadie, associate professor and director of the Applied Limnology Lab at the University of Michigan suggests that this is due to the ‘lake being so large and its depth plus a variety of factors such as inflows and outflows, seasonality, and its surrounding geology’. Thus it appears that although Lake Michigan has similar depths to some of the other Great Lakes, it has the ability to remain at cooler temperatures.
In the summer, Lake Michigan can experience extremes of temperature which by August can bring warm surface temperatures affecting major cities such as Milwaukee. On the other hand in winter months, the lake can freeze over, bringing a spell of subzero temperatures to its coastlines. In some winter months lake ice can even form as far as 50 miles offshore, forming a characteristic ice arch that stretches across the lake.
For greater understanding in the fluctuation of Lake Michigan temperatures, the US Army Corps of Engineers circumnavigate the lake to detect seasonal variances. This data is then made available for meteorologists, research scientists and recreationalists to analyse, with their research enabling locals to make informed decisions.
Due to Lake Michigan’s size and elusive depths, forecasting colder temperatures is a continual challenge. Cold fronts, mixed solutions and eddies hindering ice formation are all barriers that meteorologists and lake forecasters alike take into consideration when assessing the lake’s temperatures. With modern predictive models now being developed to give residents an intensified awareness in published forecasts, the ability to map and predict temperatures within a helpful time frame are key learning experiences for all.
The Formation of Ice
When temperatures reach subzero, Lake Michigan’s water can begin to form an icy layer, referred to as ‘slushy ice.’ This is generally a first indicator to colder temperatures, with further cold fronts causing the slushy ice to thicken, forming secure layers. During extremely cold periods and when still air masses dominate, Lake Michigan has the capability to form a total ice cover, a rather rare and impressive display.
Unlike other Great Lakes with relatively sudden freezing and thawing, the freeze pattern of Lake Michigan follows a gradient from shallow bays to deep water. The shallow bays tend to freeze first, postifying a nucleus of floating ice upon the lake’s surface, with the nucleus gradually extending towards the deeper waters on the lake. This process can be further affected by oceans of streams, islands or naturally occurring shapes.
When considering total ice coverage, only about three times a century does Lake Michigan experience this, with the last reported instance in February of 1979. Thus despite it being a rare occurrence, locals and interested onlookers alike should take note, as the breath-taking spectacle can bring a unique charm and beauty to the lake.
The Extent of the Impact
Damaging extreme temperatures and ice formation can result in major problems for Lake Michigan and its surrounding ecology. Recently this has been amplified by human impositions and land alteration, such as the construction of cities and skyscrapers, which limit the lake’s natural way of functioning.
The lake’s extreme temperatures can affect freshwater marine species, especially with extended periods of ice formation. With temperatures three degrees colder than usually found, and with insufficient food accessible during these times, locals have noticed the decline in population in the Whitefish species from Lake Michigan’s waters.
Moreover the decline in population of whitefish has had a direct causative for the revenues produced from commercial fishing, as well as the recreational activities that had been highly supported along the lake. While Lake Michigan’s colder temperatures had been considered of less importance in comparison with other Great Lakes, this study demonstrates the drastic influence its extreme temperatures can have on surrounding habitats and species.
The Issue of Algae
Due to the extreme temperatures of Lake Michigan, low oxygen levels form which in turn allow for the spread of excess nutrients. This can result in an algal bloom, speeding up the eutrophication process that occurs when algae and aquatic plants die, leading to a reduction in oxygen in its waters.
Furthermore, species such as Asian carp, sea lamprey and zebra mussels have also been able to proliferate in Lake Michigan, undeterred by the extreme temperatures. These species reproduce quickly and have caused much detriment to its local waters, with carp consuming vital algae foods, and mussels entering areas of the lake where it has already been disturbed. Consequently, the colder temperatures provided by Lake Michigan have enabled these species to expand, with fishing regulations and other preventative measures put in place.
Reverse Effect of Air Temperatures
Whilst air temperatures often remain separate from its aquatic counterparts, research by the U.S. Environmental Protection Agency (EPA) highlights the relationship between these two. Generally, when the air is colder Lake Michigan releases heat to its surroundings due to the ‘thermal efflux’ process. As such, this reverse effect can result in warmer Lake Michigan waters when air temperatures are lower.
In addition to this, the ‘thermal efflux’ process can also have an impact on air temperatures during summer time. This occurs due to the colder waters allowing cooling air to blow to the south, cooling temperatures in the process. The effects of this can especially be noticed in one of its major cities, Chicago, which since the 1900s has shown a major cooling effect due to Lake Michigan’s thermal efflux.
The Need for Human Interaction
With an estimated 20 million local residents in the vicinity of Lake Michigan, humans have an undeniable presence in the lake’s health. Whilst an array of initiatives are in place to protect it and to avoid unnecessary alterations, the need to care for and preserve the lake remains.
The effect of human interaction and non-sustainable practices, such as those of recreational sports, can cause huge disruptions and setbacks to the health of the lake, compromising its unique and sought-after characteristics. These risks include beach closures, further eutrophication and the invasion of unwanted species—all of which pose risk to the environmental balance of the lake and nearby habitats.
Ultimately, Lake Michigan’s cold temperatures are a major contributor to its uniqueness between the Great Lakes. This warrants still further exploration in order to establish an inclusive understanding of its processes, changes and effects. Uncovering all these complexities will require the collective knowledge and resourcefulness of both the local and scientific community, who are responsible for the conservation of the lake for future generations.
The Effect of Climate Change
Research into the effects of climate change on Lake Michigan highlights how further extreme cold temperatures can occur more frequently in certain parts of the lake. This can be attributed to the increased rate of evaporation and sunshine which in turn can reduce water levels and increase temperatures.
Whilst the actual phenomenon of climate change can be observed along the full length of Lake Michigan’s 3,000 miles of coastline; the evidentness is most undeniable near its northern tip in Wisconsin. Here the higher temperatures often disrupt the process of ice formation, a subtle sign of increased temperatures.
In order to produce an accurate prediction of the impacts of climate change on Lake Michigan, continued research is required in order to provide a better understanding of this ongoing modern phenomenon. With the continual monitoring of air and water temperatures, the river mouth currents and species thrive and risks, pertinent data can be used to document and prevent further detriments that may occur in the future.
Exploring New Technologies
The exploration into Lake Michigan has since developed from local knowledge to state-of-the-art discoveries. Traditional fishing practices, previously passed down from longstanding local communities, have now been replaced by modern technologies to detect senses of fish, establishing a contemporary approach towards fishing.
Moreover technologies are now being used to predict and locate the movements of Whitefish, enabling them to make informed decisions on where to invest their efforts ahead of time. This technological advancement can then be used to establish a more sustainable fishing practice and support the lake’s health.
In addition to this, more advanced technologies are continually being developed in order to understand the nuanced workings of Lake Michigan, the details of which are yet to be uncovered. Whilst this can allow for a better understanding of its movements, temperatures and inhabitants, of most significance is the human component, ensuring the long-term survival of the lake.
Conclusion
The expansive and cold depths of Lake Michigan have long provided a home to its species and a source of beauty to its onlookers. With observations of its temperatures dating back to the 1800s, Lake Michigan is an essential component to its localities, whilst also providing a greater understanding can the entire Great Lakes region.
Whilst it remains a continual pursuit of understanding all its complexities, the progress in technological advances and research initiatives into its temperatures and species provide a hopeful foundation for its conservation, in order to preserve it for future generations.
