The undersigned, as a Section 16 reporting person of Spire Global, Inc.
(the "Company"), hereby constitutes and appoints Ananda Martin, Thomas Krywe,
Allan Bowie, Sanjai Mathur and Amanda Bradley the undersigned's true and lawful
attorneys-in-fact to:

        1.  complete and execute Forms 3, 4 and 5 and other forms and all
            amendments thereto as such attorneys-in-fact shall in their
            discretion determine to be required or advisable pursuant to Section
            16 of the Securities Exchange Act of 1934 (as amended) and the rules
            and regulations promulgated thereunder, or any successor laws and
            regulations, as a consequence of the undersigned's ownership,
            acquisition or disposition of securities of the Company; and

        2.  do all acts necessary in order to file such forms with the
            Securities and Exchange Commission, any securities exchange or
            national association, the Company and such other person or agency as
            the attorneys-in-fact shall deem appropriate.

        The undersigned hereby ratifies and confirms all that said attorneys-in-
fact and agent shall do or cause to be done by virtue hereof.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the Company
assuming, any of the undersigned's responsibilities to comply with Section 16 of
the Securities Exchange Act of 1934 (as amended).

        This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

        This Power of Attorney is executed as of the date set forth below.

                             Signature: /s/ William Porteous

                             Print Name: William Porteous

                             Dated:  March 16, 2021