'''
U.S. Standard Atmosphere (Range: -0.611 to 1,000 km), 1976

This subpackage defines the following functions:

expo.py
    expo - Estimate the air densities at given geometric or geopotential altitudes 
           above the sea level using a exponential atmosphere model.
ussa76.py

isa - Implements the International Standard Atmosphere(ISA) Model up to 86km. 

lapse_tp - Calculate the temperature and pressure at a given geopotential altitude above base of a specific layer.
'''