@jaffadog
Thank you so much,your js has solved my problem and made me understand something.

@xGord
Thank you so much,your url link has solved my problem,and I seem to have got why.

when I practiced examples from http://api.windyty.com/examples/hello_world/
I got a problem below:
Redirect at origin 'https://www.windyty.com' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://api.windyty.com' is therefore not allowed access.

Actually,I have two questions about Windyty.
First one, Is there a API for Android or IOS?
Second one , How can I set 3D map?I can't find the way to set that...
Thank you for reading this topic!And sorry about my bad English skill.