How to keep a cloud observation record in ten minutes

Two looks at the same view

A useful cloud note can begin with three things: how much of your visible sky contains cloud, what the shapes look like, and what changes when you look again. Allow about ten minutes, with two observations five minutes apart. Paper and a pencil are enough; the printable sheet below is optional.

Repeated sketches of a fixed sky view are an established observation activity; UCAR uses this approach in its classroom guide. Here you will also separate hidden areas from cloud, then test what two notes allow you to conclude. The activity does not measure the whole sky or predict the weather.

1. Choose a view you can find again

Stand or sit somewhere safe and comfortable, away from traffic. Keep the Sun hidden behind an opaque building or other solid object throughout the activity; never look directly at it. Use your unaided eyes. A view through a window is fine for this exercise: note reflections, glass or a narrow opening if they limit what you can see.

Pick two fixed landmarks to mark the sides of your view, such as a chimney and a tree. Note your position and whether you are sitting or standing. Sketch the landmarks before the clouds. For the second look, return to the same position and use the same boundaries.

Write the date and local time. Record a compass direction only if you know it; “toward the courtyard” is better than an invented north.

2. Separate cloud from things that hide your view

Cloud cover describes the fraction of sky occupied by visible clouds. The WMO recommends an open site for estimating the whole sky. Here, restrict your estimate to the sky you can actually see inside your chosen view. A roof or tree is an obstruction, not a cloud; the sky behind it remains unknown.

GLOBE also distinguishes an overcast sky, almost or entirely covered by clouds, from a sky obscured by phenomena such as fog or smoke. If you cannot tell what you are seeing, record “uncertain” and describe the difficulty. A grey view alone does not settle the distinction.

On your sheet, keep two separate notes: “View blocked by…” and “Clouds occupy… of the visible sky in this view”. Use rough words such as none seen, a small part, about half, most or all. These are notebook descriptions, not official reporting categories. If you cannot make an estimate, leave it uncertain.

3. Describe a shape before giving it a name

• Outline: rounded patches, thin streaks, a broad sheet or a mixture. Put them in the view: “thin streaks above the chimney”, not just “some clouds”.
• Edges and gaps: sharp or fuzzy edges; broad blue gaps or narrow openings. Draw a few outlines rather than shading every detail.
• Appearance: bright upper edges, a darker underside or a faint veil. Record what you can see without turning a colour into a forecast.

Keep the name optional

The Met Office describes cloud forms using features such as layers, heaps and wisps. Those words help you begin a description; one resemblance does not establish a scientific cloud type. Leave the name blank or write “possible…” if you later compare it with a guide. A small sketch cannot supply an unobserved height or hidden structure.

4. Look again after five minutes

Write the second time and repeat the sketch from the same place. Compare the positions of edges and gaps against your fixed landmarks. Do not move your view to follow a particularly interesting patch.

Describe the change narrowly: “the gap above the chimney is wider” or “no clear change noticed”. The WMO advises watching how clouds evolve, but two sketches alone do not establish wind speed, prove that a patch is the same cloud, or explain why its outline changed. If your viewpoint shifted, write that down before comparing amounts.

A completed example

This is an invented example to show how to fill in the record; it is not a reported weather observation.

What does the example support?

It supports a change in one visible gap. It does not support “the whole sky became clearer”, an exact percentage change or a rain forecast. Keeping the same rough amount at both times is a valid result. If the difference is too small to judge, “uncertain” preserves more information than a forced answer.

Try this quick check

A roof hides half your chosen view. No cloud is visible in the remaining sky. Should you write “50% cloud”?

No. Write “no clouds seen in the visible part; roof blocks the rest”. A hidden area is not evidence of cloud or clear sky. On another day, use the same viewpoint if you want to compare your notes.

Keep your record, or take the next step

The sheet is a personal observation exercise. If you want to contribute observations to GLOBE, use its own current instructions and reporting process; this limited-view record is not a substitute for them.

Sources & further reading

• UCAR Center for Science Education — Drawing Clouds Inside the Lines
• WMO International Cloud Atlas — Total cloud cover and cloud amount
• GLOBE Observer — Taking Clouds Observations
• Met Office — Clouds
• WMO International Cloud Atlas — Identifying clouds