Unit 11: Climate
How weather averaged over decades sorts the planet into climate zones, and the geologic evidence showing how and why that climate has already changed.
7 topics · 21 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
What Makes Climate Different From Weather
- How it worksHow does averaging weather patterns over 30 years turn day-to-day weather into a long-term climate classification?
- Common mistakeWhy doesn't one unusually cold winter disprove a long-term warming trend in the climate?
- Ties togetherHow do daily weather events like fronts and storms add up over decades into a region's overall climate?
Your turn1 of 2
A region's 30-year average temperature is 17 degrees Celsius, but one unusually cold winter averaged 5 degrees Celsius. By how many degrees did that winter deviate from the long-term average?Latitude and Climate Zones
- How it worksHow does sunlight hitting the equator at a steep angle and the poles at a shallow angle set up Earth's climate zones?
- How it worksWalk me through why direct sunlight at the equator spreads over a smaller area than that same sunlight at high latitude.
- Common mistakeWhy isn't a location's temperature decided by latitude alone, with nothing else affecting it?
Your turn1 of 2
A beam of sunlight spreads over an area proportional to 1 divided by the sine of the angle it strikes the ground at. Direct overhead sunlight at the equator strikes at 90 degrees, while sunlight at a high latitude strikes at only 36 degrees. Roughly how many times more spread out, and so how many times less intense, is that high-latitude sunlight compared to the equator's?What Causes Global Wind Belts
- How it worksHow does warm air rising at the equator and cool air sinking near 30 degrees latitude set up a Hadley cell?
- How it worksWalk me through how the Coriolis effect bends straight-line winds into curving global wind belts.
- Common mistakeWhy isn't the Coriolis effect a real force pushing on the wind, rather than a result of Earth's own rotation?
Your turn1 of 2
Trade winds near the equator blow from nearly the same direction almost every single day, year after year. Why do trade winds near the equator blow in nearly the same direction almost every single day?How Mountains and Oceans Shape Regional Climate
- How it worksHow does air rising, cooling, and dropping its moisture on a mountain's windward side create a rain shadow on the far side?
- Going furtherWhat happens to a region's climate when a warm ocean current runs along its coast instead of a cold one?
- Ties togetherHow does a large ocean's slow-changing temperature moderate the climate of the coastline right beside it?
Your turn1 of 2
One side of a mountain range stays lush and green with heavy rainfall, while the other side, just a short distance away, is a dry desert. Why does one side of a mountain range get drenched in rain while the other side stays a desert?Evidence for Past Climate Change: Ice Cores and Tree Rings
- How it worksHow do trapped air bubbles and layered ice inside a core record both past temperature and past carbon dioxide levels?
- How it worksWalk me through counting a tree's growth rings to reconstruct which past years were wet and which were dry.
- Ties togetherHow do ice cores, tree rings, and ocean sediment layers all independently agree on the same past climate record?
Your turn1 of 2
An ice core layer trapped 294 thousand years ago sits at a depth where each meter of ice represents about 72 years of accumulated snowfall. About how many meters deep is that layer?The Greenhouse Effect
- How it worksHow do greenhouse gases let sunlight in but trap the heat that Earth radiates back out?
- How it worksWalk me through incoming sunlight warming Earth's surface and outgoing heat getting absorbed by greenhouse gases.
- Common mistakeWhy isn't the natural greenhouse effect itself the problem that climate scientists are worried about?
Your turn1 of 2
Earth's average surface temperature sits comfortably above freezing today, but calculations show it would plunge far below freezing without any atmosphere trapping heat. Why would Earth be a frozen, uninhabitable planet without any greenhouse gases in its atmosphere at all?Modern Climate Change: Causes and Evidence
- How it worksHow does burning fossil carbon add carbon dioxide to the atmosphere faster than natural cycles can absorb it?
- Common mistakeWhy doesn't a shrinking hole in the ozone layer mean the same thing as solving climate change?
- Ties togetherHow does a measured spike in atmospheric carbon dioxide line up with a matching spike in global temperature?
Your turn1 of 2
Atmospheric carbon dioxide has risen from about 284 parts per million in preindustrial times to about 419 parts per million today. By what percentage has atmospheric carbon dioxide increased?