earth science

Snow line

Snow line is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Snow line rather than just read about it. In short: The climatic snow line is the boundary between a snow-covered and snow-free surface. The actual snow line may adjust seasonally, and be either significantly higher in elevation, or lower.

Key takeaways

Snow line belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Snow line to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Snow line from memory before moving on to harder problems.

Reference excerpt

The climatic snow line is the boundary between a snow-covered and snow-free surface. The actual snow line may adjust seasonally, and be either significantly higher in elevation, or lower. The permanent snow line is the level above which snow will lie all year.

Background Snow line is an umbrella term for different interpretations of the boundary between snow-covered surface and snow-free surface. The definitions of the snow line may have different temporal and spatial focus. In many regions the changing snow line reflect seasonal dynamics. The final height of the snow line in a mountain environment at the end of the melting season is subject to climatic variability, and therefore may be different from year to year. The snow line is measured using automatic cameras, aerial photographs, or satellite images. Because the snow line can be established without on-the-ground measurements, it can be measured in remote and difficult to access areas. Therefore, the snow line has become an important variable in hydrological models. The average elevation of a transient snow line is called the "climatic snow line" and is used as a parameter to classify regions according to climatic conditions. The boundary between the accumulation zone and the ablation zone on glaciers is called the "annual snow line". The glacier region below this snow line was subject to melting in the previous season. The term "orographic snow line" is used to describe the snow boundary on surfaces other than glaciers. The term "regional snow line" is used to describe large areas. The "permanent snow line" is the level above which snow will lie all year.

Snow lines of global regions The interplay of elevation and latitude affects the precise placement of the snow line at a particular location. At or near the equator, it is typically situated at approximately 4,500 metres (15,000 ft) above sea level. As one moves towards the Tropic of Cancer and Tropic of Capricorn, the parameter at first increases: in the Himalayas the permanent snow line can be as high as 5,700 metres (19,000 feet). Beyond the Tropics, the snow line becomes progressively lower as the latitude increases, to just below 3,000 metres (9,800 ft) in the Alps and falling all the way to sea level itself at the ice caps near the poles.

In addition, the relative location to the nearest coastline can influence the elevation of the snow line. Areas near a coast might have a lower snow line than areas of the same elevation and latitude situated in a landmass interior due to more winter snowfall and because the average summer temperature of the surrounding lowlands would be warmer away from the sea. (This applies even in the tropics, since areas far from the sea will have larger diurnal temperature ranges and potentially less moisture, as observed with Kilimanjaro and presently glacier-free Mount Meru.) A higher elevation is therefore necessary to lower the temperature further against the surroundings and keep the snow from melting. Furthermore, large-scale oceanic currents such as the North Atlantic Current can have significant effects over large areas (in this case warming northern Europe, extending even to some Arctic Ocean regions). In the Northern Hemisphere the snow line on the north-facing slopes is at a lower elevation, as the north-facing slopes receive less sunlight (solar irradiance) than south-facing slopes. The converse will occur in the Southern Hemisphere.

Glacier equilibrium line The glacier equilibrium line is the point of transition between the accumulation zone and ablation zone. It is the line where the mass of these two zones is equal. Depending on the thickness of the glacier, this line can seem as though it is leaning more towards one zone but it is determined by the actual mass of ice in either zone. The rates of ablation and accumulation can also be used to determine the location of this line. This point is an important location to use in determining whether a glacier is growing or shrinking. A higher glacier equilibrium line will indicate that the glacier is shrinking, whereas a lower line will indicate that the glacier is growing. The terminus of a glacier advances or retreats based on the location of this equilibrium line. Scientists are using remote sensing to better estimate the locations of this line on glaciers around the world. Using satellite imagery, scientists are able to identify whether the glacier is growing or receding. This is a very helpful tool for analyzing glaciers that are difficult to access. Using this technology we can better gauge the effects of climate change on glaciers around the world.

Records The highest mountain in the world below the snow line is Ojos del Salado.

See also Frost line Frost line (astrophysics) Glacier High Alps Ice cap climate Tree line

References Charlesworth J.K. (1957). The quaternary era. With special reference to its glaciation, vol. I. London, Edward Arnold (publishers) Ltd, 700 pp. Flint, R. F. (1957). Glacial and Pleistocene geology. John Wiley & Sons, Inc., New York, xiii+553+555 pp. Kalesnik, S.V. (1939). Obshchaya glyatsiologiya [General glaciology]. Uchpedgiz, Leningrad, 328 pp. (in Russian) Tronov, M.V. (1956). Voprosy svyazi mezhdu klimatom i oledeneniem [The problems of the connection between climate and glaciation]. Izdatel'stvo Tomskogo Universiteta, Tomsk, 202 pp. (in Russian) Wilhelm, F. (1975). Schnee- und Gletscherkunde [Snow- and glaciers study], De Gruyter, Berlin, 414 pp. (in German) Braithewaite, R.J. and Raper, S.C.B (2009). "Estimating Equilibrium Line Altitude (ELA) From Glacier Inventory Data." Annals of Glaciology, 50, pp. 127–132. doi:10.3189/172756410790595930. Leonard, K.C., and Fountain, A.G. (2003). "Map-Based Methods for Estimating Glacier Equilibrium-Line Altitudes." Journal of Glaciology, vol. 49, no. 166, pp. 329–336., doi:10.3189/172756503781830665. Ohmura, A., Kasser, P., and Funk, M. (1992). "Climate at the Equilibrium Line of Glaciers." Journal of Glaciology, vol. 38, no. 130, pp. 397–411., doi:10.3189/S0022143000002276. Carrivick, J.L., Lee, J. and Brewer, T.R. (2004). "Improving Local Estimations and Regional Trends of Glacier Equilibrium Line Altitudes." Geografiska Annaler: Series A, Physical Geography, vol. 86, no. 1, pp. 67–79. JSTOR 3566202. Benn, D.I., and Lehmkuhl, F. (2000). "Mass balance and equilibrium-line altitudes of glaciers in high-mountain environments." Quaternary International, 65/66, pp. 15–29. doi:10.1016/S1040-6182(99)00034-8

Footnotes

Illustrations

Worked examples

Example 1 — a first encounter with Snow line

Start with the simplest possible case. Write down what Snow line claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Snow line before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Snow line ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Snow line

In research: Snow line appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Snow line in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Snow line is common in secondary-school and first-year university syllabi. It links to neighbouring topics Climate zones, Montane ecology, Snow, so understanding it makes those chapters shorter.
In everyday life: Look for Snow line outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Snow line in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Snow line means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Snow line out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Snow line in simple terms?

The climatic snow line is the boundary between a snow-covered and snow-free surface. The actual snow line may adjust seasonally, and be either significantly higher in elevation, or lower.

Why does Snow line matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Snow line?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Snow line.