Atmospheric Motion Scales Ordering

This solution explains how to arrange different atmospheric motion scales based on their horizontal size.

Understanding Horizontal Scales

Atmospheric phenomena vary significantly in their horizontal extent. We need to compare the typical sizes of:

• (a) Small eddies
• (b) Planetary waves
• (c) Fronts
• (d) Synoptic cyclones

Comparing Scale Sizes

The general order of horizontal scales, from smallest to largest, is determined as follows:

• (a) Small eddies: These represent turbulence and are the smallest, typically measured in meters to a few kilometers.
• (c) Fronts: Weather fronts are boundaries between air masses. Their horizontal extent is typically hundreds of kilometers, often considered smaller in characteristic scale than full synoptic systems.
• (d) Synoptic cyclones: These are large low-pressure systems like mid-latitude cyclones, spanning roughly 1,000 to 3,000 kilometers horizontally.
• (b) Planetary waves: These are the largest-scale atmospheric waves (e.g., Rossby waves), with wavelengths often exceeding 4,000 kilometers and extending across continents or oceans.

Final Scale Arrangement

Arranging the given scales in increasing order of their horizontal dimensions yields:

1. Small eddies (a)
2. Fronts (c)
3. Synoptic cyclones (d)
4. Planetary waves (b)

The sequence is therefore (a), (c), (d), (b).