How do I create a scrolling sky?

You spawn the cloud prefab above the map, have a starting point marked, have the cloulds move at a specific rate across the sky. Once They reach beyond a certain point, you set their position to the starting point.

sorry if this code has errors... i havent tested

 public Int Multiplyer;
 void Update()
 {
 gameObject.GetComponent<Transform>().Position += Vector3.up * multiplyer
 }

change the vector3 to whatever you might need... like Vector3.Down or left or whatever.. Attach this to the cloud

Here is something I wrote a while back that will spawn randomly sized clouds with random speed. Will need a prefab of the cloud and they will spawn around the CloudMaker

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CloudMaker : MonoBehaviour
 {
     public Cloud cloudTemplate;
 
     public Vector2 spawnHeight = new Vector2(3, 4);
     public float SpawnFrequency = 2;
     public float SpawnWidth = 200;
 
     private float lastSpawn = 0;
 
     // Update is called once per frame
     void FixedUpdate ()
     {
         if (lastSpawn >= SpawnFrequency)
         {
             var cloud = Instantiate(cloudTemplate, transform, false);
             cloud.Initialize();
 
 
             var y = Random.Range(spawnHeight.x, spawnHeight.y);
             var x = SpawnWidth / 2 * cloud.MoveDirection.x;
             var z = SpawnWidth / 2 * cloud.MoveDirection.z;
             cloud.transform.position = new Vector3(x, y, cloud.transform.position.z);
 
             lastSpawn = 0;
         }
         else
         {
             lastSpawn += Time.fixedDeltaTime;
         }
 
     }
 }

Attach this to the Cloud Prefab

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class Cloud : MonoBehaviour
 {
     public Vector3 MoveDirection { get { return m_moveDirection; } }
 
     public Vector2 ScaleRange = new Vector2(0.25f, 1);
     public Vector2 SpeedRange = new Vector2(0.025f, 0.05f);
 
     
     public float MaxLife = 3;
 
     private Vector3 m_moveDirection = Vector2.zero;
     private float life;
     private float moveSpeed;
     
     public void Initialize()
     {
         // Randomzie speed and scale
         m_moveDirection = new Vector3(Random.Range(-1.0f, 1.0f), 0, Random.Range(-1.0f, 1.0f));
         moveSpeed = Random.Range(SpeedRange.x, SpeedRange.y);
 
         float scale = Random.Range(ScaleRange.x, ScaleRange.y);
         transform.localScale = new Vector2(scale, scale);
     }
 
     IEnumerator Start()
     {
         yield return new WaitForSeconds(MaxLife);
         Destroy(gameObject);
     }
 
     void FixedUpdate ()
     {
         Vector3 move = m_moveDirection * moveSpeed;
         transform.position += move;
     }
 }
 

using UnityEngine; using System.Collections;

/// /// 天空盒子的控制 /// public class SkyBoxController : MonoBehaviour { [SerializeField] private Material[] skyBoxMaterials;

 /// <summary>
 /// 当前天空盒子的索引
 /// </summary>
 private int skyBoxIndex = 0;

 /// <summary>
 /// 是否从暗到量
 /// </summary>
 private bool isToLight = true;

 /// <summary>
 /// 当前天空盒子的亮度
 /// </summary>
 private float currentLight = 1;

 /// <summary>
 /// 天空盒子的最小亮度
 /// </summary>
 [SerializeField]
 private float minLight = 1;

 /// <summary>
 /// 天空盒子的最大亮度
 /// </summary>
 [SerializeField]
 private float maxLight = 4;

 /// <summary>
 /// 天空盒子亮度的变化速度
 /// </summary>
 [SerializeField]
 private float changeSpeed = 0.01f;

 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update ()
 {
     if (Input.GetKeyDown(KeyCode.A))
     {
         ChangeSkyBox();
     }

     ChangeSkyBoxArgs();

 }

 /// <summary>
 /// 改变当前天空盒子
 /// </summary>
 private void ChangeSkyBox()
 {
     skyBoxIndex++;
     if (skyBoxIndex > 3)
         skyBoxIndex = 0;
     RenderSettings.skybox = skyBoxMaterials[skyBoxIndex];
     RenderSettings.skybox.SetFloat("_Rotation", 0);
 }

 /// <summary>
 /// 改变天空盒子的参数
 /// </summary>
 private void ChangeSkyBoxArgs()
 {
     if (isToLight)
     {
         currentLight += changeSpeed;
         if (currentLight > maxLight)
             isToLight = false;
         RenderSettings.skybox.SetFloat("_Exposure", currentLight);
     }

     if (!isToLight)
     {
         currentLight -= changeSpeed;
         if (currentLight < minLight)
             isToLight = true;
         RenderSettings.skybox.SetFloat("_Exposure", currentLight);
     }

     float value = RenderSettings.skybox.GetFloat("_Rotation");
     RenderSettings.skybox.SetFloat("_Rotation", value + 0.006f);
 }

}