GEOGRAPHY

A new visualization shows where Earth’s rain falls—and when. (Geographical)

Create your own rainfall map with MapMaker Interactive’s precipitation layer.

Educators, scroll down for a quick list of key resources in our Teachers’ Toolkit.

Discussion Ideas

• According to the good folks at Geographical, “each grid cell in the new precipitation map is resized according to the total amount of rain (and other precipitation) in that area.” Besides rain, what are some other examples of precipitation? Take a look at our encyclopedic entry for some help.
  • Precipitation is any type of water that forms in the Earth’s atmosphere and then falls onto the surface of the Earth. Some examples of precipitation include:
    • sleet. Sleet is rain that freezes before it reaches Earth.
    • hail. Hail is precipitation that falls as solid ice. (Unlike sleet, which is liquid when it forms and freezes as it falls to Earth, hailstones form as a solid in the cloud.)
    • snow. Snow is precipitation that falls in the form of ice crystals. When snow falls in the form of a ball instead of soft flakes, it is called graupel.
    • fog. Fog, or clouds at ground level, are often considered a form precipitation.

• Take a look at the Geographical map, in which regions grow and shrink according to the precipitation they receive. Precipitation balloons Southeast Asia from nearly invisible to enormous in the early summer. What’s going on there? This encyclopedic entry might help.
  • That’s the impact of the summer monsoon. As winter ends, warm, moist air from the southwest Indian Ocean blows toward countries like India, Sri Lanka, Bangladesh, and Myanmar. The summer monsoon brings a humid climate and torrential rainfall to these areas.
    • Southeast Asia’s ballooning is also impacted by the winter monsoon, which blows from the northeast between October and April. Winter monsoons are sometimes associated with droughts.

• Besides the monsoon-driven precipitation of Southeast Asia, what other regions experience strikingly varied seasonal precipitation patterns?
  • northern South America
  • sub-Saharan Africa
  • northern East Asia
  • Australia (influenced by its own monsoon!)

• What regions experience relatively stable precipitation?
  • Europe
  • northern North America
  • New Zealand

• Use our precipitation map to find your own region. Compare the annual precipitation on our map with the seasonal data available through Geographical. When is your “rainy season”?

TEACHERS’ TOOLKIT

Geographical: Wet Lands

Nat Geo: Precipitation and Rainfall map

(extra credit!) WorldClim: Global Climate Data (download the data yourself!)

Nat Geo: What is precipitation?

Nat Geo: What is a monsoon?