When using curl (or libcurl) to retrieve a document from an https-source, the following error occurs:

# curl https://some.url.com/
curl: (60) SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

The error is shown because the CA-certificate cannot be found in the local CA-certiciate store that curl uses.