Understanding Sun and Shade at the Crag

Whether you’re chasing the sun or trying to avoid it, a little bit of knowledge about how the sun casts shadows can make or break your climbing day. In our quest for the best conditions of the day, you might think that most climbers know how to find sun or shade, but a surprising amount of people seem to be mystified when they turn up to a crag and the sun isn’t doing what they expected. 

To be fair, the orientation of the sun is quite complicated. The earth is moving in space, so the sun isn’t shining on it in exactly the same way every minute of every day. The earth’s elliptical orbit, the 23.5 degree tilt of its axis, time of year, latitude and longitude, and immediate topography all affect where and when there will be shade and the length of the shadows.

Some guidebooks offer pictograms, signaling to the reader that a climb receives all-day, morning, or afternoon sun or shade. If you’re someone who relies on the guidebook to direct you to the optimal spot but are at a loss when this information isn’t offered in the book, this article is for you.

A good place to start is knowing that due to the earth’s rotation, the sun rises in the east and sets in the west. This means that west-facing climbs receive shade in the morning and sun in the afternoon, while east-facing climbs receive sun in the morning and shade in the afternoon. 

Next, it is useful to know that due to the tilt of the earth, shadows have a northerly projection in the northern hemisphere and a southerly projection in the southern hemisphere. This means that if you want all-day shade and you’re climbing in the northern hemisphere, you should seek a north-facing wall. If you’re in the southern hemisphere and would like all-day shade, choose climbing that faces south. Conversely, if you are looking for full-day sun in the northern hemisphere, you should seek climbing that faces south, and in the southern hemisphere, climbing that faces north.

Finally, the length of shadow depends on the time of year, position of the sun in the sky, latitude of the location, and immediate topography. In the northern hemisphere, the sun appears higher in the sky in the summer and lower in the winter. The higher the sun, the shorter the shadow, and the lower the sun, the longer the shadow. This means that some climbs that receive a little bit of sun in the summer may receive none at all in the winter if there is, for example, a mountain obstructing the sun while it is in its lower winter position. This can certainly make planning more tricky. If you want to be very sure about when an area receives sun and for how long, apps like Shadowmap are able to provide you with all of the nitty gritty details.

Below is a quick reference that is basic and does not account for all factors, but it is a good place to start. This reference can also help you to make your own quick calculations about rock that faces southeast or northwest, for example.

In the northern hemisphere:

• Morning sun – east-facing rock
• Morning shade – west-facing rock
• Afternoon sun – west-facing rock
• Afternoon shade – east-facing rock
• All day sun – south-facing rock
• All day shade – north-facing rock

In the southern hemisphere:

• Morning sun – east-facing rock
• Morning shade – west-facing rock
• Afternoon sun – west-facing rock
• Afternoon shade – east-facing rock
• All day sun – north-facing rock
• All day shade – south-facing rock