Error: Object reference not set to an instance of an object.

An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.

I'm trying to make a game for this class I'm taking. I started getting this error after trying to make an array of objects.
In the game you're a tornado chaser, so I have a class for city and a class for the tornado. I'm not going to post my main form unless someone wants me to but it creates ten instances of city.

Public Class City
Public cityName As String
Public cityNum As Integer
Public temperature As Integer
Public windSpeed As Integer
Public nTemperature As Integer
Public nWindSpeed As Integer
Public sTemperature As Integer
Public sWindSpeed As Integer
Public wTemperature As Integer
Public wWindSpeed As Integer
Public eTemperature As Integer
Public eWindSpeed As Integer
Public weatherType As Integer = CInt(2 * Rnd() + 1)
Public tornadoN(cityNum) As Object
Public tornadoS(cityNum) As Object
Public tornadoE(cityNum) As Object
Public tornadoW(cityNum) As Object

Public Sub New(ByVal name As String, ByVal num As Integer)
cityName = name
cityNum = num
set_weather_type()
End Sub

Sub set_weather_type()

If weatherType = 1 Then
set_weather1()
ElseIf weatherType = 2 Then
set_weather2()
ElseIf weatherType = 3 Then
set_weather3()
End If
End Sub

Sub set_weather1()
temperature = CInt(90 * Rnd() + 70)
windSpeed = CInt(5 * Rnd())
nTemperature = CInt(90 * Rnd() + 70)
nWindSpeed = CInt(5 * Rnd())
sTemperature = CInt(90 * Rnd() + 70)
sWindSpeed = CInt(5 * Rnd())
wTemperature = CInt(90 * Rnd() + 70)
wWindSpeed = CInt(5 * Rnd())
eTemperature = CInt(90 * Rnd() + 70)
eWindSpeed = CInt(5 * Rnd())
End Sub


Sub set_weather2()
temperature = CInt(60 * Rnd() + 40)
windSpeed = CInt(18 * Rnd() + 1)
nTemperature = CInt(60 * Rnd() + 40)
nWindSpeed = CInt(18 * Rnd() + 1)
Dim tornadoN(cityNum) As Tornado
tornadoN(cityNum).set_tornado(weatherType)
sTemperature = CInt(60 * Rnd() + 40)
sWindSpeed = CInt(18 * Rnd() + 1)
Dim tornadoS(cityNum) As Tornado
tornadoS(cityNum).set_tornado(weatherType)
wTemperature = CInt(60 * Rnd() + 40)
wWindSpeed = CInt(18 * Rnd() + 1)
Dim tornadoW(cityNum) As Tornado
tornadoW(cityNum).set_tornado(weatherType)
eTemperature = CInt(60 * Rnd() + 40)
eWindSpeed = CInt(18 * Rnd() + 1)
Dim tornadoE(cityNum) As Tornado
tornadoE(cityNum).set_tornado(weatherType)
End Sub

Sub set_weather3()
temperature = CInt(50 * Rnd() + 35)
windSpeed = CInt(30 * Rnd() + 5)
nTemperature = CInt(50 * Rnd() + 35)
nWindSpeed = CInt(30 * Rnd() + 5)
Dim tornadoN(cityNum) As Tornado
tornadoN(cityNum).set_tornado(weatherType)
sTemperature = CInt(50 * Rnd() + 35)
sWindSpeed = CInt(30 * Rnd() + 5)
Dim tornadoS(cityNum) As Tornado
tornadoS(cityNum).set_tornado(weatherType)
wTemperature = CInt(50 * Rnd() + 35)
wWindSpeed = CInt(30 * Rnd() + 5)
Dim tornadoW(cityNum) As Tornado
tornadoW(cityNum).set_tornado(weatherType)
eTemperature = CInt(50 * Rnd() + 35)
eWindSpeed = CInt(30 * Rnd() + 5)
Dim tornadoE(cityNum) As Tornado
tornadoE(cityNum).set_tornado(weatherType)
End Sub

End Class




Public Class Tornado

Dim fLevel As Integer
Dim speed As Integer
Dim size As Integer

Sub set_tornado(ByVal type)
If type = 2 Then
set_tornado2()
Else
set_tornado3()
End If
End Sub

Sub set_tornado2()
fLevel = CInt(3 * Rnd() + 1)
If fLevel = 1 Then
speed = CInt(90 * Rnd() + 70)
size = CInt(80 * Rnd() + 60)
ElseIf fLevel = 2 Then
speed = CInt(70 * Rnd() + 50)
size = CInt(60 * Rnd() + 40)
Else
speed = CInt(50 * Rnd() + 30)
size = CInt(40 * Rnd() + 20)
End If

End Sub

Sub set_tornado3()
fLevel = CInt(5 * Rnd() + 4)
If fLevel = 4 Then
speed = CInt(120 * Rnd() + 90)
size = CInt(110 * Rnd() + 80)
Else
speed = CInt(175 * Rnd() + 120)
size = CInt(150 * Rnd() + 110)
End If
End Sub

End Class

What is your question? What is not working? Any error message? What line is the error on? Step debug.

An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.


That is the error message i get. It doesn't tell me what line its on. In debug on the error list it says 0. I know it has something to do with the parts of the code where I make objects of the Tornado class, because it worked till I put those in there:

Dim tornadoN(cityNum) As Tornado

TornadoN(cityNum).set_tornado(weatherType)

Sorry, now I see the first line in your post does cover the error info. Hope someone else responds to your issue. I have no experience with user-defined classes and have absolutely no idea what 'Exception.InnerException' means, looking at MS help on the topic didn't clarify for me.

I think I might know the problem. Is it possible to make an object within an object. because my program makes a city object in the main form then the city makes a tornado object.