Latitude or Parallel: The Horizontal Markings on Earth

Think of Earth as a giant stack of pancakes 🍽️. Each pancake represents a parallel—a line of latitude running horizontally around the globe. These latitudes, help us measure how far north or south a place is from the equator.

What is Latitude?

• Latitude is the angular distance of a place north or south of the equator, measured in degrees from the Earth’s center.
• These lines run parallel to the equator and never meet.
• The equator is 0° latitude, while the North Pole is 90° N and the South Pole is 90° S.

Why is a Degree of Latitude Not Uniform?

You might assume that the distance between two latitude lines is always the same, but it slightly varies because Earth is not a perfect sphere—it is flattened at the poles.

• At the Equator, the distance of one degree of latitude is 110.57 km.
• At 45° latitude, it increases to 111.13 km.
• At the Poles, it is 111.7 km.
• On average, we consider it 111 km (69 miles) per degree.

This slight variation occurs because the Earth bulges at the equator and is compressed at the poles.

Important Parallels of Latitude

Apart from the equator (0°), North Pole (90° N), and South Pole (90° S), there are four other crucial latitudes:

1. Tropic of Cancer (23½° N) – The northernmost point where the Sun is directly overhead at noon once a year (Summer Solstice, June 21).
2. Tropic of Capricorn (23½° S) – The southernmost point where the Sun is directly overhead at noon once a year (Winter Solstice, December 21).
3. Arctic Circle (66½° N) – Marks the region where at least one full day of continuous daylight and one full day of darkness occur each year.
4. Antarctic Circle (66½° S) – The same phenomenon as the Arctic Circle but in the Southern Hemisphere.

Latitudinal Heat Zones of the Earth

The Sun doesn’t shine equally everywhere. Depending on latitude, different regions receive different amounts of heat, creating three major heat zones.

1. Torrid Zone (The Hottest Zone)

• Lies between the Tropic of Cancer (23½° N) and the Tropic of Capricorn (23½° S).
• The midday sun is overhead at least once a year in every place within this zone.
• This area receives maximum heat due to direct sunlight.
• Example: Countries like India, Brazil, and Indonesia fall in this zone.

2. Temperate Zones (Moderate Climate)

• Located between the Tropic of Cancer and the Arctic Circle (Northern Hemisphere) and between the Tropic of Capricorn and the Antarctic Circle (Southern Hemisphere).
• The Sun never shines directly overhead in these zones, and the angle of sunlight decreases as you move away from the tropics.
• These areas experience moderate temperatures, with distinct seasons—summer, winter, autumn, and spring.
• Example: Most of Europe, the USA, and southern Australia fall in this zone.

3. Frigid Zones (The Coldest Regions)

• Found beyond the Arctic Circle (66½° N) in the Northern Hemisphere and the Antarctic Circle (66½° S) in the Southern Hemisphere.
• The Sun never rises high in the sky, and its rays are always slanting, leading to extreme cold.
• These regions experience polar nights and midnight sun, where the sun does not set for months in summer and does not rise for months in winter.
• Example: Antarctica, Greenland, and northern parts of Canada and Russia belong to this zone.

Final Thought: Why Do Latitudes Matter? Latitudes don’t just help in locating places; they define climatic zones, seasons, and life patterns on Earth. From the blazing heat of the tropics to the frozen silence of the poles, latitudes shape our world in ways we often overlook.