Expedition 25 The Subtropics

Expedition 25 The Subtropics

Expedition 25 On Expedition 25, we'll explore the world at twenty-five degrees north and south latitude (written as 25°N and 25°S latitude). On the map above, each of these latitude lines circles Earth about 1, 725 miles (2, 775 km) north or south of the equator. Even though these latitudes are far apart, the climate at both of them is similar because they are the same distance from the equator. What do you think the climate in these areas is like? (Hint: Bring plenty of water-you're going to need it! )

Beyond the Tropics Traveling at 25°N and 25°S latitude, we're just outside the tropical zone, or tropics, which is the region of Earth that is closest to the equator. The boundaries of the tropical zone are the Tropic of Cancer at 23. 5N latitude and the Tropic of Capricorn at 23. 5°S latitude. The regions we'll be traveling to lie in the latitudes just beyond the tropics in the subtropical zone.

Recipe for Making Deserts Unlike the hot, rainy tropical zone near the equator, the subtropics receive very little rain. That's because high pressure in the atmosphere keeps hot, dry air stuck in place over the subtropics. That same high pressure also keeps rainfall in the subtropics to a minimum-less than ten inches per year in many places. The result of these climate patterns is a predictable band of deserts that circle Earth at these latitudes. Hop in the plane and let's go visit some of them!

Deserts in the North For hours, you've been flying over northern Africa at25°N latitude. You are over the world's largest desert, the Sahara. The word Sahara means “ desert" in Arabic, the language spoken in much of North Africa. The Sahara is as big as the entire United States. As you look at the desert from high above, you see dunes-huge mountains of sand that look like golden ocean waves--but there are few signs of people.

Cairo, Egypt-City on the Nile You land at Cairo, Egypt, located at30°N latitude. When you step off the plane, the first things you notice are grit in your mouth and the sting of dust in your nose. Sand from the Sahara swirls through the air and covers everything. This big capital city is home to several million people. The Nile River flows through the center of Cairo. It is Egypt's main source of water.