Author ContributionsCGS and FKB contributed equally to the article; they conceptualized and designed the study and planned the pre-registration. CGS processed the data and conducted the analyses. FKB with LMG and NCO conducted the literature review and drafted the manuscript, with significant input from CGS, NS, MSW, CHJL, PM, JB, DO, TLM, CAH, IMD, and RVJ. NS and LMG prepared the figures.

The dual jet aircraft Sprites94 campaign yielded the first color imagery and unambiguously triangulated physical dimensions and heights of upper atmospheric optical emissions associated with thunderstorm systems. Low light level television images, in both color and in black and white (B/W), obtained during the campaign show that there are at least two distinctively different types of optical emissions spanning part or all of the distance between the anvil tops and the ionosphere. The first of these emissions, dubbed “sprites” after their elusive nature, are luminous structures of brief (< 16 ms) duration with a red main body that typically spans the altitude range 50–90 km, and possessing lateral dimensions of 5–30 km. Faint bluish tendrils often extend downward from the main body of sprites, occasionally appearing to reach cloud tops near 20 km. In this paper the principal characteristics of red sprites as observed during the Sprites94 campaign are described. The second distinctive type of emissions, “blue jets,” are described in a companion paper [Wescott et al., this issue].

Initial observations of a newly documented type of optical emission above thunderstorms are reported. “Blue jets,” or narrowly collimated beams of blue light that appear to propagate upwards from the tops of thunderstorms, were recorded on B/W and color video cameras for the first time during the Sprites94 aircraft campaign, June‐July, 1994. The jets appear to propagate upward at speeds of about 100 km/s and reach terminal altitudes of 40–50 km. Fifty six examples were recorded during a 22 minute interval during a storm over Arkansas. We examine some possible mechanisms, but have no satisfactory theory of this phenomenon.

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Social identity, shared grievances, and group efficacy beliefs are well-known antecedents to collective action, but existing research overlooks the fact that collective action often involves a confrontation between those who are motivated to defend the status quo and those who seek to challenge it. Using nationally representative data from New Zealand (Study 1; N = 16,147) and a large online sample from the United States (Study 2; N = 1,513), we address this oversight and demonstrate that system justification is negatively associated with system-challenging collective action, but positively associated with system-supporting collective action, for members of both low-status and high-status groups. Group identification, group-based injustice, group-based anger, and system-based dissatisfaction/ anger mediated these relationships. These findings constitute the first empirical integration of system justification theory into a model of collective action that explains when people will act collectively to challengeand, just as importantly, defend-the status quo.