(a) What is "Geostrophic Wind"? Explain the relationship between barometric slope and air circulation. (10 marks) (b) What is…

(a) Geostrophic Wind and Barometric Slope

A geostrophic wind is an idealised wind that blows parallel to straight, evenly spaced isobars, above the friction layer, because the pressure gradient force (PGF) is exactly balanced by the Coriolis force.

The barometric slope is the rate of pressure change per unit horizontal distance, seen as isobar spacing. Closely spaced isobars mean a steep slope and a strong PGF, which starts air moving from high to low pressure. As the speed rises, the Coriolis force, which grows with speed and latitude, deflects the air to the right in the Northern Hemisphere and to the left in the Southern. When the two forces are equal and opposite, the air stops crossing the isobars and moves along them.

So a steeper slope gives a faster geostrophic wind, and the wind circles low pressure anticlockwise and high pressure clockwise in the north. This explains the upper-air westerlies and jet streams. Near the equator the Coriolis force is almost zero, so the balance fails there.

(b) Ocean Ranching and Aqua-Cowboys

Ocean ranching is a form of aquaculture in which juveniles of commercial species, such as salmon, are hatched and reared in hatcheries, released into the open sea to feed on natural food, and harvested when they return or grow to market size.

Aqua-cowboys are the marine entrepreneurs, biologists and fisheries managers who run such ranches, in the way cowboys manage cattle on rangeland. They choose release sites, release the stock, monitor growth and migration, control disease and predation, and plan the harvest.

In India, the CMFRI has ranched the green tiger shrimp (Penaeus semisulcatus) in Palk Bay. Ranching lowers pressure on wild stocks and avoids feed and pollution costs of cage farming, but it needs property rights over the released stock and careful management of the genetic effects on wild populations.

(c) Natural Soil Enrichment and Food Production

Soil is enriched naturally by weathering, biological nitrogen fixation, humification of organic matter and deposition of silt.

Weathering frees calcium, magnesium and potassium from parent rock. Legume nodules with Rhizobium, and free-living Azotobacter, fix atmospheric nitrogen. Earthworms and microbes turn leaf litter into humus, which improves water retention, aeration and nutrient exchange. Rivers add fresh silt (khadar) each flood, and wind brings loess and volcanic ash.

These processes restore nutrients without fertiliser, raise yields, and allow multiple cropping. The Indo-Gangetic and Brahmaputra floodplains keep their fertility this way, supporting rice-wheat rotations and regional food security. Where enrichment is blocked, for example by erosion or flood control, farmers depend on chemical inputs.

(d) Deep Ecology and Shallow Ecology

The Norwegian philosopher Arne Næss drew the distinction in 1973.

(i) Value of nature. Shallow ecology is anthropocentric: nature is valued for its use to humans. Deep ecology is ecocentric: every living being has intrinsic worth whatever its use.

(ii) Response to crisis. Shallow ecology seeks technical fixes such as pollution control, recycling and resource efficiency within the present economy. Deep ecology seeks a change in values, lifestyle and economic structure.

(iii) Goals. Shallow ecology aims at human health and affluence. Deep ecology supports biospheric equality, wilderness protection, simpler living and a smaller human population and footprint.

(iv) Example. Emission standards for industry reflect the shallow view, while movements like Chipko, which protect forests as a whole living system, lean toward the deep view.

(e) Environmental Implications of Economic Geology

Economic geology finds and extracts minerals, ores and fuels, which are the base of industry, but it leaves heavy environmental costs.

Mining causes land degradation, loss of topsoil and forest, and habitat fragmentation. It lowers the water table and pollutes water: exposed pyrite makes acid mine drainage that carries heavy metals into rivers, as in the coalfields of Jharkhand and West Bengal, while chromite mining in Odisha's Sukinda valley has contaminated water with hexavalent chromium. Smelting and coal use emit sulphur dioxide and particulates, and blasting and tailings add noise, dust and dumps.

The remedies are environmental impact assessment, tailings and zero-discharge management, progressive reclamation and the Star Rating of mines, together with recycling of metals and a balance between extraction and conservation.