I have a pandas dataframe containing a record of lightning strikes with timestamps and global positions in the following format:
Index Date Time
You can use some unsupervised ML algorithms for improving speed. Before using ML algorithms need a do some data transformation. For example:
After data preprocessing , you can simply use one of scikit-learn clustering algorithms(http://scikit-learn.org/stable/modules/classes.html#module-sklearn.cluster), for arrange your data in clusters.KMeans good point for beginning.
Also, pay attention on NearestNeighbors(http://scikit-learn.org/stable/modules/generated/sklearn.neighbors.NearestNeighbors.html) for search concrete amount of objects in order of similarity.