Let us start arbitrarily by beginning the drawing of the 1020-mb isobar in nebraska. north platte, ne would be on a 1020-isobar line generally running north-south. three other isobar lines are noted or needed through the eastern part of the state, given the 4-millibar interval convention. these three lines will separate values where the lower value on the map remains to one side while higher values are on the other side. the pressure values of locations generally east of north platte are therefore 1020 mb.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.

Maybe a horizontal because its a pattern

Its in the national history museum and you can't se the original because its locked away in a vault