As per Koppen's climatic classification, the district in Rajasthan, which…

Concept

In Köppen's climatic classification a climate is coded by stacked letters: the first capital is the broad group (B = arid/dry), the second capital is the sub-type (W = true desert, S = steppe), and the lowercase letter is the temperature character (h = hot, where the mean annual temperature is above 18 °C). So BWh denotes a HOT DESERT climate — very low, erratic rainfall with high temperatures through the year.

Application

Western Rajasthan lies in the core of the Thar Desert, the hottest and driest tract of India. Mapping the districts against the BWh zone:

1. Identify the district that lies WHOLLY inside the hot-desert tract (not merely partly): arid, low-rainfall conditions must hold across its entire area.

2. Jaisalmer sits in the extreme west, entirely within the Thar core, and records the lowest annual rainfall in the state — its whole area is hot desert.

3. Hence the district that falls COMPLETELY under the BWh (hot desert) category is Jaisalmer.

Contrast

• Barmer — largely arid, but its area is not classed as wholly hot desert; parts grade toward a drier-steppe margin, so it is not entirely BWh.

• Bikaner — has a desert climate, yet only part of the district lies in the true BWh core while the rest sits in the transitional steppe belt.

• Jodhpur — lies in the arid zone but spans a climatic transition, so the whole district is not classified as BWh.

Note on the code

Some Rajasthan-geography sources write the western desert as BWhw, where the extra lowercase w marks a dry winter. That w is only a precipitation-seasonality sub-modifier; the governing category is still BW (arid desert) with h (hot). BWh and BWhw therefore name the same hot-desert type, and Jaisalmer is the district that falls completely within it.