Which one of the following is closely associated with westerlies? (A) Furious fifties (B) Boyle's gas law (C) Walker circulation (D) Rossby waves
(A) and (D) only
Understanding the Association with Westerlies
The question asks which phenomena are closely associated with westerlies. Westerlies are prevailing winds that blow from the west at mid-latitudes (roughly between 30° and 60° latitude) towards the poles. They play a significant role in global weather patterns.
Analyzing the Given Options
Let's examine each option to determine its association with westerlies:
- (A) Furious fifties: The "Furious Fifties" is a term used to describe the strong westerly winds found in the Southern Hemisphere, typically between latitudes 50°S and 60°S. These strong winds are a direct manifestation of the westerlies in a region with less landmass, allowing them to blow with great strength and consistency. Therefore, this is closely associated with westerlies.
- (B) Boyle's gas law: Boyle's Law is a fundamental law in physics and chemistry that describes the relationship between the pressure and volume of a gas at constant temperature. It is expressed as \(PV = k\), where \(P\) is pressure, \(V\) is volume, and \(k\) is a constant. While atmospheric processes involve gases and pressure, Boyle's Law itself is a general physical principle and is not specifically or closely associated with the *phenomenon* of westerlies.
- (C) Walker circulation: The Walker circulation is an atmospheric circulation cell along the equatorial Pacific Ocean. It is driven by differences in sea surface temperatures and atmospheric pressure between the western and eastern Pacific. It is a key component of the El Niño-Southern Oscillation (ENSO) phenomenon. While part of the larger global atmospheric circulation, it is primarily an equatorial phenomenon and is not directly or closely associated with the mid-latitude westerlies.
- (D) Rossby waves: Rossby waves (also known as planetary waves) are large-scale meanders in the jet streams of the upper atmosphere (which are components of the westerlies) and in ocean currents. They are caused by the variation of the Coriolis effect with latitude and play a crucial role in transporting heat from the tropics towards the poles and cold air from the poles towards the tropics. These waves are intrinsically linked to the dynamics of the westerlies and the jet streams. Therefore, this is closely associated with westerlies.
Conclusion on Association with Westerlies
Based on the analysis:
- "Furious fifties" are a direct manifestation of strong westerlies.
- "Rossby waves" are large-scale atmospheric waves that occur within the westerlies and jet streams.
- "Boyle's gas law" is a general physical law not specifically tied to westerlies.
- "Walker circulation" is an equatorial phenomenon.
Thus, both Furious fifties and Rossby waves are closely associated with westerlies.
Summary of Associations
| Option | Association with Westerlies |
|---|---|
| (A) Furious fifties | Closely associated (strong westerlies) |
| (B) Boyle's gas law | Not closely associated (general gas law) |
| (C) Walker circulation | Not closely associated (equatorial phenomenon) |
| (D) Rossby waves | Closely associated (waves within westerlies/jet streams) |
Therefore, the phenomena closely associated with westerlies are (A) Furious fifties and (D) Rossby waves.
Revision Table: Key Atmospheric Concepts
| Concept | Description | Association with Westerlies |
|---|---|---|
| Westerlies | Prevailing winds from the west in mid-latitudes (30-60°) | The core phenomenon |
| Furious fifties | Strong westerlies in the Southern Hemisphere (50-60°S) | Direct manifestation of strong westerlies |
| Rossby waves | Large-scale waves in jet streams and westerlies | Integral to the dynamics and behavior of westerlies |
| Jet Stream | Fast-flowing, narrow air currents in the atmosphere, part of westerlies | Strongly associated (Rossby waves occur in jet streams) |
| Polar Front | Boundary between cold polar air and warmer mid-latitude air where westerlies are strong | Closely associated (Westerlies are strong near the polar front) |
Additional Information: Dynamics of Westerlies
Westerlies are driven by the temperature difference between the tropics and the poles and the Coriolis effect. Warm air rises at the equator and moves poleward, while cold air sinks at the poles and moves equatorward. The Earth's rotation deflects this poleward-moving air towards the east (in both hemispheres), creating the westerlies in the mid-latitudes.
- Northern Hemisphere Westerlies: Typically weaker and more variable due to larger landmasses and mountain ranges.
- Southern Hemisphere Westerlies: Stronger and more consistent due to fewer landmasses at those latitudes, leading to terms like "Roaring Forties," "Furious Fifties," and "Screaming Sixties" to describe their increasing strength with latitude.
- Role of Rossby Waves: Rossby waves in the westerlies (specifically the jet streams) are critical for weather patterns. They cause the movement of high and low-pressure systems, influencing storms and temperature variations in mid-latitude regions. The amplitude of these waves can change, affecting whether weather patterns are relatively zonal (west-to-east flow) or more meridional (north-south meanders).
Important Questions from Climatology
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1. Anticyclones are high pressure systems.
2. Air in the centre of the system must be subsiding.
3. Anticyclones are characterized by converging winds.
How many of the above statements is/are correct?
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