How to use Transparency

Search for a town, glen or hill, use your location, or choose a spot on the map.

Tap the long box and type a name, then tap the name that appears. Or tap the round target beside it and allow location. If you tap Don’t allow, nothing is broken. Type a place name instead. Or tap Choose on a map, tap the spot, then tap Use this spot.

The big copper word is how clear the air looks for the night at this spot.

There are four words: Excellent, Good, Fair and Poor. The row of four under the text shows where tonight sits, with the current word in copper.

Under the word is a short reason that says what is in the way, such as Low cloud, or Nothing in the way. Then come the place, the date, and the hours from dusk to dawn.

A plain line says whether tonight is worth going out. When it is not, it may say whether the next few nights look any better. The small print is worth reading too. It is a forecast of the air, not a promise the stars will be there.

Look across the hours to see when the air is clearest.

Hour by hour is a row of bars from dusk to dawn. A taller copper bar means clearer air. A dot under an hour marks true dark.

The word above the bars is for the middle of these hours. Tap a bar to read that hour on its own.

Across the night shows what is making the air milky.

Each row is one thing that can get between you and the stars: Haze, Smoke, Dust, Humidity and Thin high cloud. A longer copper bar means more of it in the air.

Haze is the milky column. Smoke and dust are the particles. Humidity is the damp. Thin high cloud is cirrus.

Each row has a word and a number. Read the word first. The number is the reading behind it.

You want to know whether tonight is worth going out. Search for the place. Read the word and the reason. Then look through the hours for a clear stretch, and see what is in the way.

In these pictures, the Cairngorms on Sunday 4 October was Poor, with low cloud, and nothing in the next few nights was clear enough. The air itself was not dirty. The damp and the cloud were what shut the night. Another place that night was Excellent, with nothing in the way.

The word is a forecast of the air, not a promise of stars, and it will not be the same when you look.

Some titles have a small arrow. Tap a title to learn more. Tap it again to close it.

• What transparency is — see a clear hour compared with a milky hour.
• Saved places — rename a place or remove it.

Save places you check often so you can open them again from the tiles below the search box.

When a place is open, tap Save place. You can put it in a shortcut instead of one you already have, or tap Add as another. Tap Cancel if you change your mind.

The copper word on a tile is tonight’s word for that place. To rename or remove a place, open the Saved places box.

Use Share to make a picture of tonight.

The picture shows the place on a map, the word, the reason, and the hours from dusk to dawn. Tap Share to send the picture and the link, or Save picture to keep the image. The link opens Transparency at the same place.

Transparency shows how clear the air will be. Two other apps cover the rest of the plan, and under the result you will find a tile for each.

Lid shows the chance of a lid at the same place. A lid holds haze and damp air underneath it, so a hill above one can have clearer air than the valley below. Sky Contours shows where the moon washes out the sky over the same place, from the same dusk to the same dawn.

Tap Open in Lid or Open in Sky Contours. Each opens at the same place.