Cold Front Calculator

Cold Front Calculator#

Adapted from: “Modern Fortran: Building Efficient Parallel Applications” by Milan Curcic (Manning)

Program to Calculate the Temperature due to a Cold Front#

program cold_front

    implicit none
    
    real :: temp1 = 12 ! degrees C
    real :: temp2 = 24 ! degrees C
    real :: dx = 960   ! km
    real :: c = 20     ! km / hr
    real :: dt = 24    ! hours
    
    real :: res        ! result in degrees C
    
    res = temp2 - c * (temp2 - temp1) / dx * dt
    
    print *, "Temperature after ", dt, &
             "hours is ", res, "degrees"
             
end program cold_front

The following explanation is given by “Code Copilot” within ChatGPT 4.

The Fortran program cold_front is designed to calculate the change in temperature as a cold front moves over a given distance and time. The program uses a simple linear model to interpolate or extrapolate temperature changes based on the movement of the cold front. Here’s a detailed explanation of each component and the underlying calculations:

Variables:#

  • temp1 (12 degrees C): Initial temperature at the starting point.

  • temp2 (24 degrees C): Initial temperature at a point 960 km away from the starting point.

  • dx (960 km): The distance between two points where the initial temperatures are measured.

  • c (20 km/hr): Speed of the cold front moving through the area.

  • dt (24 hours): Time period over which the temperature change is calculated.

Calculation:#

  • Temperature Difference Calculation:

    • temp2 - temp1 computes the temperature difference between the two points.

  • Temperature Change Rate:

    • (temp2 - temp1) / dx calculates the rate of temperature change per kilometer.

  • Temperature Change Over Time:

    • c * (temp2 - temp1) / dx * dt computes the total temperature change over dt hours, considering the speed of the cold front. The term c * dt effectively calculates the distance covered by the cold front in dt hours. Multiplying this distance by the rate of temperature change per kilometer gives the total change in temperature over that distance.

Result:#

  • res: The resulting temperature after the cold front has moved for dt hours. The calculation temp2 - c * (temp2 - temp1) / dx * dt adjusts the initial temperature at temp2 by the amount the temperature is expected to change due to the cold front’s movement. The subtraction here is due to the interpretation that moving through the temperature gradient causes a decrease from the starting point at temp2.

Output:#

  • The program prints the resulting temperature after dt hours, indicating how much the temperature has changed due to the cold front’s progression.

Simplified Formula Explanation:#

  • The formula calculates how much the temperature decreases as the cold front moves from temp2 towards temp1. This is based on the linear change in temperature over the distance dx, scaled by how far the cold front moves in dt hours.

Usage:#

This simple program can be used in educational settings to demonstrate basic principles of linear interpolation and applying rates over time, or in a basic meteorological context to estimate temperature changes without complex modeling. It is a straightforward example of applying basic physics and arithmetic operations in a programmatic context.

Program Compilation and Execution#

The above program is compiled and run using Fortran Package Manager (fpm):

import os
root_dir = ""
root_dir = os.getcwd()

code_dir = root_dir + "/" + "Fortran_Code/Cold_Front_Calculator"

os.chdir(code_dir)

build_status = os.system("fpm build 2>/dev/null")

exec_status = os.system("fpm run 2>/dev/null")

 Temperature after    24.0000000     hours is    18.0000000     degrees