Why It’s a Big Deal to Fly Across the Equator

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Crossing the equator, the imaginary line that bisects the Earth, will change your view on global geography, weather patterns and aviation navigation.

I have crossed the equator more than 50 times, and I always look at the navigation computer displays as we count down to zero latitude. For me, flying over the hemispheric boundary is a navigational thrill that few people get to experience. It also means we can be swapping winter for summer: Australia can be basking in heat while it’s ‑40°C in Winnipeg, and a July flight to Chile can mean a reunion with ski season. And a bonus of flying in a north‑south direction is the lack of jet lag: A 10‑hour flight may stay within a single time zone, so your built‑in clock won’t miss a beat.

Weather fronts are rare near the equator – it’s just one hot and humid air mass. Tropical storms and hurricanes (typhoons) do not cross the line, and jet streams rarely do. But the equator does have its own unique weather phenomenon: the Intertropical Convergence Zone (ITCZ), a belt of thunderstorms undulating north and south, nourishing the rainforests of the Amazon, Congo and Indonesia. Since the troposphere (the layer of Earth’s atmosphere in which we live) is highest at the equator, these rainmakers can rise way up; weather radar helps us to fly around them. As a meteorologist, I can also rely on geosynchronous weather satellites parked 35,786 kilometres above the equator to guide me.

Way down at ground level as we cross the line, the widest part of the Earth is spinning on its axis at 1,670 kilometres an hour. That’s something to contemplate as you take in the view.

February 8, 2021

Equator Data

  • Trade winds from the northern and southern hemispheres converge near the equator, forcing air up into the atmosphere where it forms clouds. This Intertropical Convergence Zone (ITCZ) shifts north and south with the sun, creating the tropics’ wet and dry seasons, the monsoons and other weather patterns.

An infographic of the equator
   Illustration: Alamy
  • 4 — The Earth has four equators: the one shown on maps; a thermal equator that migrates north and south slightly with the seasons; the magnetic equator that follows the Earth’s magnetic field; and the celestial equator, the plane of the terrestrial equator intersecting the celestial sphere surrounding the planet.

  • The equator is divided into 360 degrees of longitude. Each time zone consists of roughly 15 degrees, hence 24 hours.

  • To be in “the doldrums” – that expression to describe someone feeling low in spirits or energy – refers to maritime weather near the equator: high humidity, hot light winds and sudden rain.

Ask the Captain

Send your aviation and operations queries to: douglas.morris@aircanada.ca

Portrait of Air Canada's Captain Doug Morris
Photo: Reynard Li

Doug Morris is an author, meteorologist, instructor and Air Canada captain on the Boeing 787.