Weather and climate

The sky above a particular place

Looking up at a cloud and comparing summer with winter involve different scales of explanation. The cloud course follows water in the air and the forms clouds take. The seasons course asks how date and latitude affect daylight, then considers climate zones. Read them together to connect a familiar view of the sky with the geometry behind seasonal changes. Keep a description of the cloud you see separate from a claim about the climate of the place where you are standing.

Cloud forms before climate groups

Start with Clouds. The opening units explain cloud formation and naming. Low clouds include cumulus, stratus and stratocumulus; another unit distinguishes middle and high clouds. Cumulonimbus receives its own treatment as the thunderstorm cloud, followed by a unit on reading the sky. Learn the differences in shape and height together, so a name points to features you can actually describe rather than just a word on a flashcard.

Then read Seasons and climate zones. It begins with why seasons happen and how day length varies with latitude. Polar day and polar night, the tropics and the subsolar point make the geometry more specific. The course introduces the Köppen climate groups and ends with seasons in the southern hemisphere. That last comparison is a useful check on explanations built only around the seasons at home.

Compare two settings and hold one fixed

The cloud menu lets you switch between forms in the water-cycle model. Compare the low stratus layer with high cirrus and the vertical extent of cumulonimbus. In the final cloud unit, start at 25 °C and change to 5 °C, watching the model rather than assuming the picture will stay the same. Record which setting you changed and what the scene shows.

In the seasons model, move the date slider at a fixed latitude, then keep the date fixed while changing latitude. The close view makes differences in daylight easier to inspect. Compare a northern setting with the southern setting used in the final unit. Changing one input at a time helps you explain which result belongs to the date and which belongs to the observer’s position.

Explanations to check against the model

Do not use one season’s weather as the definition of a climate zone. The course separates climate groups from the mechanism producing seasons. Likewise, learning a cloud name should not replace describing its height and form. Return to the formation unit when a label has become detached from the process. Use the unit questions to test your explanation without the diagram in front of you, then reopen the model to check the part you could not explain. The aim is an account that still makes sense when the location or date changes.