Why in the News?
Hurricane Hilary, a major tropical cyclone, hit Southern California alongside a 5.1 magnitude earthquake. This unusual “hurriquake” event led to the first-ever tropical storm warning for Southern California. The cyclone originated off Mexico’s coast, making landfall on Baja California before affecting California. Although no immediate damage was reported from the earthquake, experts linked Hurricane Hilary to climate change. The US National Hurricane Center and President Biden took action to manage the situation, while California experienced record rainfall.
What is a Hurricane?
A hurricane is a sizable, swirling storm featuring powerful winds that originates above warm tropical oceans. It’s referred to as a hurricane in the Atlantic and eastern Pacific Ocean, a typhoon in the western Pacific Ocean, and a cyclone in the Indian Ocean. These storms are recognized by their low-pressure cores, spiral rainbands, and sustained winds surpassing 74 miles per hour (119 kilometres per hour). They have the potential to inflict considerable destruction through forceful winds, intense rainfall, storm surges, and flooding.
Formation process:
- The ascent of warm, moisture-laden air into the atmosphere results in cooling, causing water vapour to condense and form clouds. This rising air leads to the creation of a region of reduced atmospheric pressure over the designated area.
- As the air continues its upward movement, a tropical depression takes shape. These depressions are characterised by the emergence of thunderstorms accompanied by winds ranging from 37 to 62 km/h.
- The upward movement of air persists, with a counterclockwise rotation. This progression culminates in the development of a tropical storm, featuring winds exceeding 63 km/h. This phase generates potent thunderstorms.
- Upon attaining wind speeds surpassing 119 km/h, the storm transforms into a hurricane. It’s important to note that only a mere one percent of tropical storms progress to the hurricane stage
Hurricane Hilary Characteristics:
- Pacific coast’s infrequent tropical storms and hurricanes due to the ocean’s nature.
- Hurricanes require ocean temperature above 26°C for formation.
- Below 26°C, hurricanes don’t form or weaken rapidly on cooler water.
- The US east coast experiences high temperatures during hurricane season, while the west coast is colder.
- In the Atlantic, Gulf Stream carries warm equatorial waters northward, unlike Pacific’s cold currents.
- Cold currents along the Pacific’s west coast steer colder water from higher latitudes, discouraging hurricanes.
- Vertical wind shear, change in upper-level wind speed, disrupts hurricane structure.
- Strong upper-level winds displace warm temperatures, limit vertical ascent, hindering hurricane formation.
- Eastern Pacific’s wind shear stronger than Gulf of Mexico’s, leading to fewer western coast hurricanes.
- Wind steering patterns, like trade winds, direct hurricanes towards the east coast, away from the west coast.
- Hurricanes from the eastern Pacific follow a west-northwest trajectory, moving away from the coast.
