Lessons 6 · 1 lessons · Sh. M. Sharipov, V. N. Fedorko, N. I. Safarova, V. A. Rafiqov. Geography (Applied geography), Grade 10, 1st edition. “O‘zbekiston milliy ensiklopediyasi” State Scientific Publishing House, Tashkent, 2017
6
The geographic envelope and its general laws
Textbook: pp. 24–28
GoalExplain the structural levels, properties and general laws of the geographic envelope (integrity, cycling, rhythmicity).
New words
geocomponent · geokomponentlaw of integrity · bir butunlik qonuniyaticycling of matter and energy · modda va energiyaning aylanma harakatirhythmicity · ritmiklik
Explanation
The geographic envelope has three structural levels: geocomponent (rocks, water, air, soil, plants and animals), geospheric (lithosphere, hydrosphere, atmosphere, biosphere – the vertical structure) and geosystem (the horizontal structure). Its uniqueness is that only here does water exist in three states, soil form, and life and human society exist, and solar energy change its form. By the law of integrity the components are linked: change in one leads to change in others; the envelope is not a simple sum of components but a qualitatively new system. The cycling of matter and energy (water, air, biological and other cycles) maintains this unity. Rhythmicity is the repetition of phenomena at certain intervals: daily (the Earth rotating on its axis), annual (revolution round the Sun and axial tilt), within-century (for example the roughly 11-year solar activity cycle) and multi-century and tectonic cycles. Knowing these laws matters for forecasting natural processes and for using resources sensibly.
Worked examples
During an ice age water accumulated in glaciers and the World Ocean level fell by about a hundred metres. The floor of a shallow strait 40 m deep stood 100 − 40 = 60 m above the water as dry land, so animals could cross between continents. This illustrates integrity: climate → ice → sea level → relief → organisms.
The solar activity cycle lasts about 11 years. In 55 years there are 55 ÷ 11 = 5 such cycles. This is an example of within-century rhythmicity.
Class activity
“Chain”: students stand in a circle; the first says “rainfall decreased” and each next student continues with a consequence (river flow → plants → soil → animals → human economy). The chain shows the links between components.
Practice
1
Name the three structural levels of the geographic envelope.
Geocomponent, geospheric and geosystem.
2
What kind of rhythm does the Earth's rotation on its axis produce? Give one natural example.
Daily rhythm: for example, the change of air temperature during the day or photosynthesis occurring only in daylight.
3
If the solar cycle lasts 11 years, how many full cycles occur in 66 years? (Number only.)
6
4
Why does mass logging affect not only plants but also river regimes?
Because components are linked (integrity): forest holds and evaporates rainfall; when it is cut, runoff speeds up, soil is washed away and the river's water regime changes.