Question 1

With reference to high pressure and low pressure areas on surface maps, which of the following statements is or are correct?

Accepted Answer

Concept overview / definition High pressure and low pressure are commonly drawn on weather maps as H and L centres, but these labels are not fixed absolute numbers. In practice, whether a location is treated as a high or a low depends on how its pressure compares with the pressures at nearby locations. The teacher illustrates this with values like 10, 11 and 12 millibars where the same value can behave as high in one comparison and low in another, showing that the concept is relative. Why the correct option is correct Statement 1 is correct because a place is called high pressure only when its value is higher than the surrounding values, and low pressure when it is lower than its neighbours. Statement 2 is also correct, as seen in the example where 11 millibars is higher than 10 but lower than 12, so it can act as high in one pair and low in another. Together these statements capture the idea that the labels high and low are meaningful only with reference to a chosen neighbourhood and cannot be fixed globally. Why the other options are incorrect Statement 3 wrongly claims that high and low pressure areas are defined by fixed absolute thresholds that are the same everywhere on Earth. This contradicts the explanation that the same numerical value can be high or low depending on context. Therefore any option that treats high and low as universal fixed categories is incorrect. As a result, options that include Statement 3 as correct cannot be chosen if you follow the relative nature described in the class discussion. UPSC exam tip / common confusion Many candidates think of high pressure and low pressure as single numbers to memorise, which leads to confusion when reading seasonal maps. In prelims, whenever a question compares pressure at different points, think in terms of relative differences rather than absolute labels. First list which point has the highest and which has the lowest value in that set and only then use the terms high and low. This habit helps you avoid traps where the examiner plays with changing reference points across diagrams.

Question 2

Regarding the concept of pressure gradient and its role in wind motion, which of the following statements are correct?

Accepted Answer

Concept overview / definition Pressure gradient is introduced in climatology to explain why winds can be gentle in some situations and very strong in others. It refers to how quickly pressure changes over a given horizontal distance, not just the absolute values at individual points. If the pressure difference between two places is large over a short distance, the pressure gradient is steep; if the difference is small or spread over a long distance, the gradient is weak, and this directly influences wind speed. Why the correct option is correct Statement 1 is correct because the teacher defines pressure gradient as the rate of change in pressure per unit horizontal distance. Statement 2 is correct since a larger difference such as from 100 to 20 units over a given distance creates a stronger push on the air, so winds move with greater speed. Statement 3 is also correct because when the pressure gradient is very small the driving force is weak, so winds tend to remain light or gentle. All three statements together summarise the link between pressure pattern and wind motion described in the lecture. Why the other options are incorrect Any option that omits one of these statements fails to reflect the full explanation of pressure gradient given in the discussion. The class example clearly connects the magnitude of pressure difference with the strength of wind, and also notes that a small gradient leads to slower motion. Options that deny the role of rate of change, or that imply wind speed is unaffected by the sharpness of the gradient, are inconsistent with the step by step reasoning used in the transcript. UPSC exam tip / common confusion In exam questions on wind speed, students sometimes focus only on the absolute values of pressure at two points and ignore the distance between them. A safer approach is to think in terms of per unit horizontal distance, just as the definition of gradient suggests. When comparing two diagrams, the one where isobars are closer together usually indicates a steeper pressure gradient and therefore stronger winds. Remember this visual shortcut when interpreting synoptic charts in prelims questions.

Climatology Questions