Q2A · Elaborate in brief any 5 causes for Cold Wave and Droughts.

Answer

Five cold-wave causes

1. Cold air intrusion. Air masses from colder regions can sharply lower local temperatures.
2. Clear nights. The ground loses heat through radiation when cloud cover is limited.
3. Light winds. In some settings light winds allow a shallow cold layer to develop near the surface.
4. Snow and cold surfaces. Snow cover and nearby cold terrain can reinforce low temperatures under suitable conditions.
5. Persistent circulation. Weather patterns can sustain cold conditions over several days. Climate change does not mean cold events become impossible.

Five drought causes and contributing factors

1. Persistent rainfall deficit. Rainfall stays below the local seasonal requirement for a sustained period. Delayed monsoon onset, long dry spells or early withdrawal reduce the water entering soil, streams and reservoirs.
2. High evaporative demand. Hot, dry and windy conditions increase evaporation and plant water demand. The same rainfall deficit can therefore produce a more severe soil-moisture shortage.
3. Large-scale circulation variability. Variations in circulation and monsoon behaviour can suppress rain over a region. ENSO can influence some Indian droughts, but not every El Niño produces drought everywhere and not every drought has this cause.
4. Excessive withdrawal relative to recharge. Over-abstraction of groundwater or surface water can intensify hydrological shortage. Water-demand pressure amplifies drought impacts; it does not itself cause a meteorological rainfall deficit.
5. Reduced storage and poor water management. Degraded catchments, loss of suitable water storage, leakage and unsuitable crop-water demand leave less usable supply during a dry period. These conditions increase drought vulnerability rather than independently proving that rainfall has decreased.

Separate the climatic trigger from the human factors that intensify water shortage. Example: a village faces deficient monsoon rainfall; high heat dries the soil faster, heavy pumping lowers groundwater, and leaky supply pipes worsen the shortage.

Source: Government of India Manual for Drought Management, hosted by NIDM: rainfall deficit, evaporative losses and water-demand indicators. This explains mechanisms, not a declaration of drought for any specific district.