Consider the following statements on 'Fog': 1. Fog is simply a cloud that forms close to the ground. 2. Radiation fog is associated with radiation cooling of the land at night. 3. Advection fog forms when moisture is blown over a cold surface and is chilled by contact. Which of the statements given above are correct ?

Fog is scientifically defined as a cloud with its base located at or very near the ground, significantly reducing visibility [4]. Statement 1 is correct as fog and clouds share the same condensation process but differ in location [5]. Statement 2 is accurate; radiation fog occurs on clear, calm nights when the land surface loses heat through terrestrial radiation, chilling the adjacent air to its dew point [3]. Statement 3 is also correct; advection fog forms when warm, moist air moves horizontally over a colder surface, causing the air to cool by contact and condense [2]. Unlike radiation fog, advection fog can occur over both land and sea and often requires a light breeze to transport the air mass. Since all three statements accurately describe the nature and specific formation mechanisms of fog types, option 4 is the correct choice.

Sources

1. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 10: Water in the Atmosphere > Fog and Mist > p. 87
2. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Fog > p. 332
3. [5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > 24.4. Forms of Condensation > p. 331
4. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > The Beaufort Wind Scale > p. 128
5. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Haze > p. 333