Anticyclone
An anticyclone is a large-scale high-pressure atmospheric system in which air spirals outward from a central high-pressure zone — clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Descending air in an anticyclone suppresses cloud formation, bringing clear skies, dry conditions, and stable weather. While anticyclones are often associated with fair weather, they can also cause persistent temperature extremes — heatwaves in summer and cold spells or frost in winter — and contribute to air pollution by trapping pollutants near the surface.
Key Formula
f = 2 × Ω × sin(φ)
LaTeX: f = 2\Omega \sin(\phi)
| Symbol | Meaning | Unit |
|---|---|---|
| f | Coriolis parameter (determines rotation direction) | s⁻¹ |
| Ω | Earth's angular velocity (7.27 × 10⁻⁵ rad/s) | rad/s |
| φ | Latitude of the system | degrees |
Worked Example
Problem
Calculate the Coriolis parameter f for an anticyclone centred at 30°N latitude.
Solution
Step 1: Ω = 7.27 × 10⁻⁵ rad/s, φ = 30°. Step 2: f = 2 × 7.27 × 10⁻⁵ × sin(30°). Step 3: sin(30°) = 0.5. Step 4: f = 2 × 7.27 × 10⁻⁵ × 0.5 = 7.27 × 10⁻⁵ s⁻¹.
Answer
Coriolis parameter f = 7.27 × 10⁻⁵ s⁻¹
Cyclone vs Anticyclone Comparison
| Feature | Cyclone | Anticyclone |
|---|---|---|
| Central Pressure | Low | High |
| Air Movement | Inward and upward | Downward and outward |
| NH Rotation | Counterclockwise | Clockwise |
| SH Rotation | Clockwise | Counterclockwise |
| Typical Weather | Storms, clouds, rain | Clear skies, dry, stable |
| Temperature Effect | Brings warm/wet air | Can cause heat or cold waves |
Interactive Tools
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Related Terms
Cyclone
A cyclone is a large-scale atmospheric system with low central pressure, around which winds spiral inward — counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis Effect. Tropical cyclones (known as hurricanes in the Atlantic and typhoons in the Pacific) are intense, warm-core systems that derive energy from warm ocean water, while extratropical cyclones are cold-core systems associated with mid-latitude weather fronts. Cyclones bring heavy rainfall, strong winds, and storm surges, and are among the most destructive natural weather phenomena.
Atmospheric Pressure
Atmospheric pressure is the force per unit area exerted by the weight of the overlying column of air in the atmosphere on any surface below it. At sea level, the standard atmospheric pressure is 101,325 Pa (or 1013.25 hPa / 1 atm), and it decreases with altitude as the mass of air above decreases. Atmospheric pressure differences drive wind and weather systems: low-pressure zones are associated with storms and clouds, while high-pressure zones bring clear, calm conditions.
Coriolis Effect
The Coriolis Effect is the apparent deflection of moving objects — including air and water — caused by Earth's rotation. In the Northern Hemisphere, objects are deflected to the right of their direction of motion; in the Southern Hemisphere, they are deflected to the left. This effect is responsible for the rotation of large-scale weather systems such as cyclones and anticyclones, as well as global wind patterns like the trade winds and westerlies.
From Greek "anti" (ἀντί) meaning "against" or "opposite," combined with "cyclone" — literally the opposite of a cyclone. The term was introduced by Francis Galton in 1861 to describe high-pressure systems with outward spiralling winds, in contrast to inward-spiralling cyclones.